update links across docs

Signed-off-by: Matthew Peveler <matt.peveler@gmail.com>

11 files changed, 88 insertions, 93 deletions

diff --git a/doc/a2x.1.txt b/doc/a2x.1.txt
index e9af286..ca4dabf 100644
--- a/doc/a2x.1.txt
+++ b/doc/a2x.1.txt
@@ -286,7 +286,7 @@ REQUISITES
 - *dblatex* (pdf, dvi, ps, tex formats):
   http://dblatex.sourceforge.net/
 - *FOP* (pdf format -- alternative PDF file generator):
-  http://xmlgraphics.apache.org/fop/
+  https://xmlgraphics.apache.org/fop/
 - *w3m* (text format):
   http://w3m.sourceforge.net/index.en.html
 - *Lynx* (text format -- alternative text file generator):
diff --git a/doc/asciidoc.txt b/doc/asciidoc.txt
index fa1e62e..6144d2a 100644
--- a/doc/asciidoc.txt
+++ b/doc/asciidoc.txt
@@ -176,14 +176,14 @@ html5::
 
 slidy::
   Use this backend to generate self-contained
-  http://www.w3.org/Talks/Tools/Slidy2/[Slidy] HTML slideshows for
+  https://www.w3.org/Talks/Tools/Slidy2[Slidy] HTML slideshows for
   your web browser from AsciiDoc documents. The Slidy backend is
   documented in the distribution `doc/slidy.txt` file and
   {website}slidy.html[online].
 
 wordpress::
   A minor variant of the 'html4' backend to support
-  http://srackham.wordpress.com/blogpost1/[blogpost].
+  https://srackham.wordpress.com/blogpost1/[blogpost].
 
 latex::
   Experimental LaTeX backend.
@@ -225,7 +225,7 @@ backend <<X101,plugins>>.
 DocBook
 -------
 AsciiDoc generates 'article', 'book' and 'refentry'
-http://www.docbook.org/[DocBook] documents (corresponding to the
+https://docbook.org/[DocBook] documents (corresponding to the
 AsciiDoc 'article', 'book' and 'manpage' document types).
 
 Most Linux distributions come with conversion tools (collectively
@@ -233,8 +233,9 @@ called a toolchain) for <<X12,converting DocBook files>> to
 presentation formats such as Postscript, HTML, PDF, EPUB, DVI,
 PostScript, LaTeX, roff (the native man page format), HTMLHelp,
 JavaHelp and text.  There are also programs that allow you to view
-DocBook files directly, for example http://live.gnome.org/Yelp[Yelp]
-(the GNOME help viewer).
+DocBook files directly, for example
+https://wiki.gnome.org/action/show/Apps/Yelp[Yelp] (the GNOME help
+viewer).
 
 [[X12]]
 Converting DocBook to other file formats
@@ -343,7 +344,7 @@ AsciiDoc::
   uses <<X13,DocBook XSL Stylesheets>>, <<X40,xsltproc(1)>> and
   `latex(1)`.
 
-[[X14]]http://xmlgraphics.apache.org/fop/[FOP]::
+[[X14]]https://xmlgraphics.apache.org/fop/[FOP]::
   The Apache Formatting Objects Processor converts XSL-FO (`.fo`)
   files to PDF files.  The XSL-FO files are generated from DocBook
   source files using <<X13,DocBook XSL Stylesheets>> and
@@ -353,7 +354,7 @@ AsciiDoc::
   The Microsoft HTML Help Compiler (`hhc.exe`) is a command-line tool
   that converts HTML Help source files to a single HTML Help (`.chm`)
   file. It runs on MS Windows platforms and can be downloaded from
-  http://www.microsoft.com.
+  https://www.microsoft.com/.
 
 AsciiDoc dblatex configuration files
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -1030,7 +1031,7 @@ outputs. The CSS class names are:
   decorators.
 
 Where '<color>' can be any of the
-http://en.wikipedia.org/wiki/Web_colors#HTML_color_names[sixteen HTML
+https://en.wikipedia.org/wiki/Web_colors#HTML_color_names[sixteen HTML
 color names].  Examples:
 
   [red]#Obvious# and [big red yellow-background]*very obvious*.
@@ -1311,7 +1312,7 @@ block the second attribute value in the AttributeList is quoted to
 ensure the 'http' macro is expanded to a hyperlink.
 
 ---------------------------------------------------------------------
-[quote,'http://en.wikipedia.org/wiki/Samuel_Johnson[Samuel Johnson]']
+[quote,'https://en.wikipedia.org/wiki/Samuel_Johnson[Samuel Johnson]']
 _____________________________________________________________________
 Sir, a woman's preaching is like a dog's walking on his hind legs. It
 is not done well; but you are surprised to find it done at all.
@@ -2464,7 +2465,7 @@ list'.  The usual syntax is `<name>:<target>[<attrlist>]` (for
 inline macros) and `<name>::<target>[<attrlist>]` (for block
 macros).  Here are some examples:
 
-  http://www.docbook.org/[DocBook.org]
+  https://docbook.org/[DocBook.org]
   include::chapt1.txt[tabsize=2]
   mailto:srackham@gmail.com[]
 
@@ -2508,16 +2509,16 @@ rendered using predefined inline macros.
 
 Here are some examples:
 
-  http://www.docbook.org/[DocBook.org]
-  http://www.docbook.org/
+  https://docbook.org/[DocBook.org]
+  https://docbook.org/
   mailto:joe.bloggs@foobar.com[email Joe Bloggs]
   joe.bloggs@foobar.com
 
 Which are rendered:
 
-http://www.docbook.org/[DocBook.org]
+https://docbook.org/[DocBook.org]
 
-http://www.docbook.org/
+https://docbook.org/
 
 mailto:joe.bloggs@foobar.com[email Joe Bloggs]
 
@@ -2623,7 +2624,7 @@ referring document.
 - The optional 'alt' attribute is also the first positional attribute,
   it specifies alternative text which is displayed if the output
   application is unable to display the image file (see also
-  http://htmlhelp.com/feature/art3.htm[Use of ALT texts in IMGs]). For
+  https://htmlhelp.com/feature/art3.htm[Use of ALT texts in IMGs]). For
   example:
 
   image:images/logo.png[Company Logo]
@@ -2735,7 +2736,7 @@ A title prefix that can be inserted with the `caption` attribute
 *********************************************************************
 If you define the `data-uri` attribute then images will be embedded in
 XHTML outputs using the
-http://en.wikipedia.org/wiki/Data:_URI_scheme[data URI scheme].  You
+https://en.wikipedia.org/wiki/Data_URI_scheme[data URI scheme].  You
 can use the 'data-uri' attribute with the 'xhtml11' and 'html5'
 backends to produce single-file XHTML documents with embedded images
 and CSS, for example:
@@ -3646,7 +3647,7 @@ refmiscinfo attributes
 ~~~~~~~~~~~~~~~~~~~~~~
 In addition to the automatically created man page <<X60,intrinsic
 attributes>> you can assign DocBook
-http://www.docbook.org/tdg5/en/html/refmiscinfo.html[refmiscinfo]
+https://tdg.docbook.org/tdg/4.5/refmiscinfo.html[refmiscinfo]
 element 'source', 'version' and 'manual' values using AsciiDoc
 `{mansource}`, `{manversion}` and `{manmanual}` attributes
 respectively. This example is from the AsciiDoc header of a man page
@@ -3678,7 +3679,7 @@ distributed `doc/latexmath.txt` file.
 
 MathJax
 ~~~~~~~
-http://www.mathjax.org/[MathJax] allows LaTeX Math style formulas to be included
+https://www.mathjax.org/[MathJax] allows LaTeX Math style formulas to be included
 in XHTML documents generated via the AsciiDoc 'xhtml11' and 'html5' backends.
 This route overcomes several restrictions of the MathML-based approaches,
 notably, restricted support of MathML by many mainstream browsers. To enable
@@ -3691,7 +3692,7 @@ you are offline (but it can be configured differently).
 LaTeXMathML
 ~~~~~~~~~~~
 /////////////////////////////////////////////////////////////////////
-There is an http://math.etsu.edu/LaTeXMathML/[extended LaTeXMathML
+There is an https://math.etsu.edu/LaTeXMathML/[extended LaTeXMathML
 version] by Jeff Knisley, in addition to a JavaScript file it requires
 the inclusion of a CSS file.
 /////////////////////////////////////////////////////////////////////
@@ -3699,7 +3700,7 @@ the inclusion of a CSS file.
 'LaTeXMathML' allows LaTeX Math style formulas to be included in XHTML
 documents generated using the AsciiDoc 'xhtml11' and 'html5' backends.
 AsciiDoc uses the
-http://www.maths.nottingham.ac.uk/personal/drw/lm.html[original
+https://www.maths.nottingham.ac.uk/plp/pmadw/lm.html[original
 LaTeXMathML] by Douglas Woodall.  'LaTeXMathML' is derived from
 ASCIIMathML and is for users who are more familiar with or prefer
 using LaTeX math formulas (it recognizes a subset of LaTeX Math, the
@@ -3733,11 +3734,11 @@ because:
 2. Version 2 is much larger.
 /////////////////////////////////////////////////////////////////////
 
-http://www1.chapman.edu/~jipsen/mathml/asciimath.html[ASCIIMathML]
-formulas can be included in XHTML documents generated using the
-'xhtml11' and 'html5' backends. To enable ASCIIMathML support you must
-define the 'asciimath' attribute, for example using the `-a asciimath`
-command-line option.  Example inline formula:
+http://asciimath.org/[ASCIIMath] formulas can be included in XHTML
+documents generated using the 'xhtml11' and 'html5' backends. To enable
+ASCIIMathML support you must define the 'asciimath' attribute, for
+example using the `-a asciimath` command-line option.  Example inline
+formula:
 
   asciimath:[`x/x={(1,if x!=0),(text{undefined},if x=0):}`]
 
@@ -3746,7 +3747,7 @@ distributed `doc/asciimathml.txt` file.
 
 MathML
 ~~~~~~
-http://www.w3.org/Math/[MathML] is a low level XML markup for
+https://www.w3.org/Math/[MathML] is a low level XML markup for
 mathematics. AsciiDoc has no macros for MathML but users familiar with
 this markup could use passthrough macros and passthrough blocks to
 include MathML in output documents.
@@ -4322,8 +4323,8 @@ compounded by redundancy if the same name is used repeatedly.
 Attribute entries can be used to make your documents easier to read
 and write, here are some examples:
 
-  :1:         http://freshmeat.net/projects/asciidoc/
-  :homepage:  http://asciidoc.org[AsciiDoc home page]
+  :1:         http://freshmeat.sourceforge.net/projects/asciidoc/
+  :homepage:  https://asciidoc.org[AsciiDoc home page]
   :new:       image:./images/smallnew.png[]
   :footnote1: footnote:[A meaningless latin term]
 
@@ -4716,7 +4717,7 @@ predefined intrinsic attributes:
    the standard output then `{docname}` is the output file name sans
    file extension.
 7. See
-   http://en.wikipedia.org/wiki/Non-English_usage_of_quotation_marks[non-English
+   https://en.wikipedia.org/wiki/Quotation_mark#Summary_table[non-English
    usage of quotation marks].
 8. The `{blockname}` attribute identifies the style of the current
    block. It applies to delimited blocks, lists and tables. Here is a
@@ -5112,7 +5113,7 @@ The AsciiDoc distribution includes 'source', 'music', 'latex' and
 |music
 |A {website}music-filter.html[music filter] is included in the
 distribution `./filters/` directory. It translates music in
-http://lilypond.org/[LilyPond] or http://abcnotation.org.uk/[ABC]
+https://lilypond.org/[LilyPond] or https://abcnotation.com/[ABC]
 notation to standard classical notation.
 
 |source
@@ -5125,7 +5126,7 @@ LaTeX source to an image that is automatically inserted into the
 AsciiDoc output documents.
 
 |graphviz
-|Gouichi Iisaka has written a http://www.graphviz.org/[Graphviz]
+|Gouichi Iisaka has written a https://www.graphviz.org/[Graphviz]
 filter for AsciiDoc.  Graphviz generates diagrams from a textual
 specification. Gouichi Iisaka's Graphviz filter is included in the
 AsciiDoc distribution. Here are some
@@ -5244,7 +5245,7 @@ Execute `:help gq` command to read about the vim gq command.
   available (see the <<X61, Example `~/.vimrc` file>>).
 - Put `set` commands in your `~/.vimrc` file so you don't have to
   enter them manually.
-- The Vim website (http://www.vim.org) has a wealth of resources,
+- The Vim website (https://www.vim.org/) has a wealth of resources,
   including scripts for automated spell checking and ASCII Art
   drawing.
 =====================================================================
@@ -5459,8 +5460,8 @@ liking you can:
    template sections. The `{empty}` attribute is useful for outputting
    trailing blank lines in markup templates.
 
-2. Use Dave Raggett's http://tidy.sourceforge.net/[HTML Tidy] program
-   to tidy asciidoc(1) output. Example:
+2. Use https://www.html-tidy.org/[HTML Tidy] program to tidy
+   asciidoc(1) output. Example:
 
    $ asciidoc -b docbook -o - mydoc.txt | tidy -indent -xml >mydoc.xml
 
@@ -5560,7 +5561,7 @@ it will be fetched from its Internet location. If you omit the
 `--valid` option the document will only be checked that it is well
 formed.
 
-The online http://validator.w3.org/#validate_by_uri+with_options[W3C
+The online https://validator.w3.org/#validate_by_uri+with_options[W3C
 Markup Validation Service] is the defacto standard when it comes to
 validating HTML (it validates all HTML standards including HTML5).
 
@@ -5878,7 +5879,7 @@ Embed images using the <<X66,data: uri scheme>>.
 Set a 'CSS signature' for the document (sets the 'id' attribute of the
 HTML 'body' element). CSS signatures provide a mechanism that allows
 users to personalize the document appearance. The term 'CSS signature'
-was http://archivist.incutio.com/viewlist/css-discuss/13291[coined by
+was https://juicystudio.com/article/css-selectors.php[coined by
 Eric Meyer].
 
 
diff --git a/doc/asciimathml.txt b/doc/asciimath.txt
index ed5e269..b51c37c 100644
--- a/doc/asciimathml.txt
+++ b/doc/asciimath.txt
@@ -1,10 +1,10 @@
 ASCIIMathML Formulae
 ====================
 
-http://www1.chapman.edu/~jipsen/mathml/asciimath.html[ASCIIMathML] is
-a clever JavaScript written by Peter Jipsen that dynamically
-transforms mathematical formulae written in a wiki-like plain text
-markup to http://www.w3.org/Math/[MathML] markup which is displayed as
+http://asciimath.org/[ASCIIMath] is a clever JavaScript written by
+Peter Jipsen that dynamically transforms mathematical formulae
+written in a wiki-like plain text markup to
+https://www.w3.org/Math/[MathML] markup which is displayed as
 standard mathematical notation by the Web Browser.  See 'Appendix E'
 in the AsciiDoc User Guide for more details.
 
@@ -25,13 +25,11 @@ page.
   characters in the formulas with a backslash, escaping is unnecessary
   if you use the double-dollar macro (for examples see the second
   formula below).
-- See the
-  http://www1.chapman.edu/~jipsen/mathml/asciimath.html[ASCIIMathML]
-  website for ASCIIMathML documentation and the latest version.
+- See the http://asciimath.org[ASCIIMath] website for ASCIIMathML
+  documentation and the latest version.
 - If the formulas don't appear to be correct you probably need to
   install the correct math fonts (see the
-  http://www1.chapman.edu/~jipsen/mathml/asciimath.html[ASCIIMathML]
-  website for details).
+  http://asciimath.org[ASCIIMath] website for details).
 - See the link:latexmathml.html[LaTeXMathML page] if you prefer to use
   LaTeX math formulas.
 
diff --git a/doc/epub-notes.txt b/doc/epub-notes.txt
index cf108e5..79f66dd 100644
--- a/doc/epub-notes.txt
+++ b/doc/epub-notes.txt
@@ -35,8 +35,7 @@ into the toc.ncx navigation control file:
    <ncx:meta name="dtb:depth" content="-1"/>
 
 Shouldn't it be a positive integer equal to the depth navPoint nesting in the
-navMap element (see
-http://www.niso.org/workrooms/daisy/Z39-86-2005.html#NavMeta)? Though epubcheck 1.05 doesn't flag it as invalid -- are they both wrong?
+navMap element? Though epubcheck 1.05 doesn't flag it as invalid -- are they both wrong?
 
 
 [[X1]]
diff --git a/doc/faq.txt b/doc/faq.txt
index 5a72a28..76f22b7 100644
--- a/doc/faq.txt
+++ b/doc/faq.txt
@@ -311,12 +311,12 @@ NOTE: link:userguide.html#X26[Comment blocks] are never displayed.
 
 
 == What is the preferred file name extension for AsciiDoc files?
-The `.txt` http://en.wikipedia.org/wiki/Text_file[text file] extension
+The `.txt` https://en.wikipedia.org/wiki/Text_file[text file] extension
 is preferred, but it's just a convention and it's not enforced by the
 software.
 
 AsciiDoc source files are human readable
-http://en.wikipedia.org/wiki/Plain_text[plain text] files which is
+https://en.wikipedia.org/wiki/Plain_text[plain text] files which is
 what the `.txt` extension is for. All text editors recognize and open
 files with a `.txt` extension. The `.txt` extension is universally
 recognized and unambiguous -- you are not left asking questions like
@@ -470,7 +470,7 @@ substitutions in the monospaced text, for example:
 == How can I generate a single HTML document file containing images and CSS styles?
 With the advent of Internet Explorer 8 all major web browsers now
 support the
-http://en.wikipedia.org/wiki/Data:_URI_scheme[data URI scheme] for
+https://en.wikipedia.org/wiki/Data_URI_scheme[data URI scheme] for
 embedded images. The AsciiDoc 'xhtml11' and 'html5' backends supports
 the data URI scheme for embedded images and by default it embeds the
 CSS stylesheet. For example the following command will generate a
@@ -636,13 +636,13 @@ b. List 2.
 
 There are a number of programs available that generate presentation
 charts from textual specification, for example
-http://home.gna.org/pychart/[Pychart] is a library for writing chart
+https://pypi.org/project/PyChart/[Pychart] is a library for writing chart
 scripts in Python. Here's an example from the 'Pychart' documentation:
 
 .barchart.py
 ---------------------------------------------------------------------
 #
-# Example bar chart (from Pychart documentation http://home.gna.org/pychart/).
+# Example bar chart (from Pychart documentation https://pypi.org/project/PyChart/).
 #
 from pychart import *
 theme.get_options()
@@ -939,8 +939,9 @@ from the command-line.
 
 == Are there any DocBook viewers?
 
-http://live.gnome.org/Yelp[Yelp], the GNOME help viewer, does a
-creditable job of displaying DocBook XML files directly.
+https://wiki.gnome.org/action/show/Apps/Yelp[Yelp], the GNOME help
+viewer, does a creditable job of displaying DocBook XML files
+directly.
 
 
 == Can you create ODF and PDF files using LibreOffice?
@@ -1358,12 +1359,12 @@ example:
 
 
 == How can I convert documents from other formats to AsciiDoc?
-You can use http://johnmacfarlane.net/pandoc/[Pandoc] to convert
-documents in http://daringfireball.net/projects/markdown/[markdown],
-http://docutils.sourceforge.net/docs/ref/rst/introduction.html[reStructuredText],
-http://redcloth.org/textile[textile],
-http://www.w3.org/TR/html40/[HTML], http://www.docbook.org/[DocBook],
-or http://www.latex-project.org/[LaTeX] to AsciiDoc.
+You can use https://pandoc.org/[Pandoc] to convert documents in
+https://daringfireball.net/projects/markdown/[markdown],
+https://docutils.sourceforge.io/rst.html[reStructuredText],
+https://www.promptworks.com/textile/[textile],
+https://html.spec.whatwg.org/[HTML], https://docbook.org/[DocBook],
+or https://www.latex-project.org/[LaTeX] to AsciiDoc.
 
 
 == How can I insert raw HTML in a document processed by a2x?
diff --git a/doc/latex-backend.txt b/doc/latex-backend.txt
index c6cbc35..c87f456 100644
--- a/doc/latex-backend.txt
+++ b/doc/latex-backend.txt
@@ -132,8 +132,9 @@ The following software is necessary for using the LaTeX backend:
 
 - An up-to-date version of https://asciidoc.org/[Asciidoc]
 - An up-to-date TeX distribution, e.g.:
-  * http://www.miktex.org/[MiKTeX] for Windows
-  * http://www.tug.org/tetex/[teTeX] for Linux
+  * https://miktex.org/[MiKTeX] for Windows
+  * https://tug.org/texlive/[teTeX] for Linux
+  * https://www.tug.org/mactex/ for macOS
 
 [[packageRequirements]]
 === TeX/LaTeX Package requirements
@@ -175,7 +176,7 @@ For more special characters take a look in the `[replacements2]` sections. `[rep
 
 === Code listing block
 
-For creating highlighted code listings I suggest the use of http://www.andre-simon.de/[Highlight] or http://www.gnu.org/software/src-highlite/[GNU Source Highlight]. Both are suited for use as Asciidoc filters.
+For creating highlighted code listings I suggest the use of http://www.andre-simon.de/[Highlight] or https://www.gnu.org/software/src-highlite/[GNU Source Highlight]. Both are suited for use as Asciidoc filters.
 
 == Known Bugs
 
diff --git a/doc/latexmathml.txt b/doc/latexmathml.txt
index e7f5a56..a1df891 100644
--- a/doc/latexmathml.txt
+++ b/doc/latexmathml.txt
@@ -1,20 +1,20 @@
 LaTeXMathML Formulae
 ====================
 
-http://www.maths.nottingham.ac.uk/personal/drw/lm.html[LaTeXMathML]
+https://www.maths.nottingham.ac.uk/plp/pmadw/lm.html[LaTeXMathML]
 capability has been added to AsciiDoc for users who are more familar
 with or prefer LaTeX math formulas to the
-https://asciidoc.org/asciimathml.html[ASCIIMathML]
+https://asciidoc.org/asciimath.html[ASCIIMath]
 notation.
 
 'LaTeXMathML' is a derivative of
-https://asciidoc.org/asciimathml.html[ASCIIMathML] -- in
+https://asciidoc.org/asciimath.html[ASCIIMath] -- in
 terms of usage the only difference it that you use the `latexmath`
 attribute instead of the `asciimath` attribute.
 
 'LaTeXMathML' processes LaTeX math formulas not arbitrary LaTeX (as
 `dblatex(1)` does). See the
-http://www.maths.nottingham.ac.uk/personal/drw/lm.html[LaTeXMathML]
+https://www.maths.nottingham.ac.uk/plp/pmadw/lm.html[LaTeXMathML]
 website for details.
 
 Here's the link:latexmathml.txt[AsciiDoc source] that generated this
diff --git a/doc/music-filter.txt b/doc/music-filter.txt
index 1daa70b..4ddf5ac 100644
--- a/doc/music-filter.txt
+++ b/doc/music-filter.txt
@@ -2,8 +2,8 @@ Music Filter
 ============
 
 The AsciiDoc distribution includes a Music Block filter that
-translates music in http://lilypond.org/[LilyPond] or
-http://abcnotation.org.uk/[ABC] notation to standard classical
+translates music in https://lilypond.org/[LilyPond] or
+https://abcnotation.com/[ABC] notation to standard classical
 notation in the form of a trimmed PNG image which is automatically
 inserted into the AsciiDoc output document (see the examples below).
 
@@ -130,9 +130,9 @@ Installation
 ------------
 In addition to AsciiDoc you will need to have installed:
 
-- http://lilypond.org/web/[LilyPond] (most Linux distributions include
+- https://lilypond.org/[LilyPond] (most Linux distributions include
   this package).
-- http://www.imagemagick.org[ImageMagick] (most Linux distributions
+- https://imagemagick.org/[ImageMagick] (most Linux distributions
   include this package).
 
 Test the music filter it by converting the test file to HTML with AsciiDoc:
diff --git a/doc/publishing-ebooks-with-asciidoc.txt b/doc/publishing-ebooks-with-asciidoc.txt
index 896b54f..61e75db 100644
--- a/doc/publishing-ebooks-with-asciidoc.txt
+++ b/doc/publishing-ebooks-with-asciidoc.txt
@@ -18,7 +18,7 @@ ifdef::blogpost[]
 endif::blogpost[]
 
 It's easy to write and publish books in
-http://en.wikipedia.org/wiki/EPUB[EPUB] and PDF formats using
+https://en.wikipedia.org/wiki/EPUB[EPUB] and PDF formats using
 https://asciidoc.org/[AsciiDoc].
 ifdef::blogpost[]
 This article was originally published on the
@@ -44,14 +44,9 @@ system.
 NOTE: A number of 'asciidoc' and 'a2x' features used in this article
 require newer versions of AsciiDoc -- version 8.6.5 or better is
 recommended. The version of
-http://wiki.docbook.org/topic/DocBookXslStylesheets[DocBook XSL
+https://github.com/docbook/wiki/wiki/DocBookXslStylesheets[DocBook XSL
 Stylesheets] used was 1.76.1.
 
-TIP: If you are experiencing 'xsltproc' errors when you run 'a2x' take
-a look at Francis Shanahan's
-http://francisshanahan.com/index.php/2011/fixing-epub-problem-docbook-xsl-asciidoc-a2x/[Fixing
-the ePub problem with Docbook-XSL/A2X/Asciidoc] blog post.
-
 
 [[X1]]
 Minimal Book
@@ -92,7 +87,7 @@ version (`minimal-book.pdf`) with 'dblatex' run:
   a2x -fpdf -dbook minimal-book.txt
 
 The distributed example PDFs were built using FOP -- if you prefer
-http://xmlgraphics.apache.org/fop/[FOP] over
+https://xmlgraphics.apache.org/fop/[FOP] over
 http://dblatex.sourceforge.net/[dblatex] use:
 
   a2x -fpdf -dbook --fop minimal-book.txt
@@ -116,7 +111,7 @@ prepackaged for your Linux distribution):
 - https://github.com/docbook/xslt10-stylesheets[DocBook XSL
   Stylesheets]
 - http://dblatex.sourceforge.net/[dblatex] (PDF file generator)
-- http://xmlgraphics.apache.org/fop/[FOP] (alternative PDF file
+- https://xmlgraphics.apache.org/fop/[FOP] (alternative PDF file
   generator)
 - https://github.com/w3c/epubcheck[epubcheck] (optional EPUB file
   validator)
@@ -128,7 +123,7 @@ The Brothers Karamazov
 ----------------------
 'The Brothers Karamazov' is an example of a multi-part book. To
 generate the AsciiDoc source I downloaded the
-http://www.gutenberg.org[Project Gutenberg] plain text source and
+https://www.gutenberg.org/[Project Gutenberg] plain text source and
 edited it manually (this took around 15 minutes). To generate the
 `brothers-karamazov.epub` EPUB file run this command:
 
@@ -145,7 +140,7 @@ edited it manually (this took around 15 minutes). To generate the
 
 |link:examples/books/brothers-karamazov.zip[brothers-karamazov.zip]
 
-|http://www.gutenberg.org/etext/28054
+|https://www.gutenberg.org/ebooks/28054
 
 |====================================================================
 
@@ -154,7 +149,7 @@ specific meta-data:
 
 ---------------------------------------------------------------------
 //
-// Text from Project Gutenburg http://www.gutenberg.org/etext/28054
+// Text from Project Gutenburg https://www.gutenberg.org/etext/28054
 //
 // Formatted for AsciiDoc by Stuart Rackham.
 //
@@ -257,12 +252,12 @@ this command:
 
 |link:examples/books/adventures-of-sherlock-holmes.zip[adventures-of-sherlock-holmes.zip]
 
-|http://www.gutenberg.org/etext/1661
+|https://www.gutenberg.org/etext/1661
 
 |====================================================================
 
 Here's a screenshot of the first page of the first chapter (rendered
-by the http://www.epubread.com/en/[Firefox EPUBReader addon]):
+by the https://www.epubread.com/en/[Firefox EPUBReader addon]):
 
 image::examples/books/sherlock-epub.png[]
 
@@ -271,7 +266,7 @@ Zip file] contains the following files:
 
 `adventures-of-sherlock-holmes.txt`::
   The AsciiDoc source (derived from the
-  http://www.gutenberg.org/etext/1661[Project Gutenberg plain text
+  https://www.gutenberg.org/etext/1661[Project Gutenberg plain text
   source]).
 
 `adventures-of-sherlock-holmes.jpg`::
@@ -302,7 +297,7 @@ specific meta-data:
 
 ---------------------------------------------------------------------
 //
-// Text from Project Gutenburg http://www.gutenberg.org/etext/1661
+// Text from Project Gutenburg https://www.gutenberg.org/etext/1661
 //
 // Formatted for AsciiDoc by Stuart Rackham.
 //
@@ -374,7 +369,7 @@ See https://asciidoc.org/faq.html#X5[this FAQ].
 Reading EPUB documents
 ----------------------
 To view and read epub files, you can use
-http://www.epubread.com/en/[EPUBReader addon], which is available for
+https://www.epubread.com/en/[EPUBReader addon], which is available for
 Firefox, Chrome / Chromium, and Opera. EPUBReader honors the book's
 CSS styling rules and renders the page as the author intended (many
 EPUB readers only process a sub-set of CSS styling rules).
@@ -388,6 +383,6 @@ Non-fiction Books and Manuals
 AsciiDoc supports a rich set of markup conventions and can generate
 reference works and technical manuals complete with tables,
 illustrations, indexes, bibliographies and appendices. All the
-examples on the http:///asciidoc.org/[AsciiDoc web site]
+examples on the https://asciidoc.org/[AsciiDoc web site]
 can be formatted as EPUB eBooks.
 
diff --git a/doc/slidy.txt b/doc/slidy.txt
index 2de5790..38f06c4 100644
--- a/doc/slidy.txt
+++ b/doc/slidy.txt
@@ -21,7 +21,7 @@ AsciiDoc has a 'slidy' backend for generating self contained 'Slidy'
 HTML slideshows.
 
 - An overview of 'Slidy' can be found here:
-  http://www.w3.org/Talks/Tools/Slidy2/
+  https://www.w3.org/Talks/Tools/Slidy2
 - AsciiDoc ships with the Slidy JavaScript a customised Slidy CSS
   file.
 - Use the 'asciidoc' `--backend slidy` command-line option to generate
diff --git a/doc/source-highlight-filter.txt b/doc/source-highlight-filter.txt
index 2c29b68..41af974 100644
--- a/doc/source-highlight-filter.txt
+++ b/doc/source-highlight-filter.txt
@@ -31,7 +31,7 @@ load time).
 
 === GNU Source Highlight
 The default highlighter is the
-http://www.gnu.org/software/src-highlite/[GNU source-highlight] which
+https://www.gnu.org/software/src-highlite/[GNU source-highlight] which
 can highlight 'html4', 'html5' and 'xhtml11' outputs.  The GNU
 source-highlight must be installed and the 'source-highlight' command
 must reside in the shell search 'PATH'.
@@ -52,7 +52,7 @@ syntax highlighter for 'xhtml11', 'html5' and 'html4' outputs (set the
   `--encoding` command-line option.
 
 === Pygments
-The http://pygments.org/[Pygments] syntax highlighter can be used for
+The https://pygments.org/[Pygments] syntax highlighter can be used for
 'xhtml11' and 'html5' outputs (set the 'source-highlighter' attribute
 to 'pygments').