diff --git a/www/Documents/index.html b/www/Documents/index.html
index 65a33f2..c5eec53 100644
--- a/www/Documents/index.html
+++ b/www/Documents/index.html
@@ -71,7 +71,7 @@ related to both education and research.
 <p>
 <ul>
 
-<li><a href="http://www.joelonsoftware.com/articles/ThePerilsofJavaSchools.html">
+<li><a href="https://www.joelonsoftware.com/2005/12/29/the-perils-of-javaschools-2/">
 The Perils of JavaSchools</a>,
 Joel Spolsky, 2005</li>
 
@@ -84,7 +84,7 @@ Successful Scheme: Programming language still going strong after 25
 years</a>,
 by Cameron Laird and Kathryn Soraiz, Sun World Online, October 2000</li>
 
-<li><a href="http://www.flownet.com/ron/papers/lisp-java.pdf">
+<li><a href="https://flownet.com/ron/papers/lisp-java.pdf">
 Lisp as an Alternative to Java</a>, Erann Gat</li>
 
 <li><a href="http://http.cs.berkeley.edu/~bh/bridge.ps">Symbolic
@@ -134,7 +134,7 @@ Press, 1996
 Scheme</cite></a>, Laurent Arditi and St&eacute;phane Ducasse,
 Eyrolles, 1996
 
-<li><a href="http://www.editionstechnip.com/F/bloch_initiation_programmation_avec_1004.asp">
+<li><a href="https://www.editionstechnip.com/fr/catalogue-detail/692/initiation-a-la-programmation-et-aux-algorithmes-avec-scheme.html">
 <cite>Initiation &agrave; la programmation avec Scheme</cite></a>,
 Laurent Bloch,  Editions Technip, 2001</li>
 
@@ -161,12 +161,12 @@ href="http://dept-info.labri.u-bordeaux.fr/~cori/Bouquins/scheme.ps">
 <cite>Passeport pour Scheme</cite></a>, Robert Cori and Pierre
 Casteran, unpublished manuscript
 
-<li><a href="http://mitpress.mit.edu/0262541483">
-<cite>The Scheme Programming Language</cite></a> (3/e), R. Kent
+<li><a href="https://www.scheme.com/tspl4/">
+<cite>The Scheme Programming Language</cite></a> (4/e), R. Kent
 Dybvig, MIT Press, 2003
 
 <li><a
-href="http://www.htdp.org/">
+href="https://htdp.org/">
 <cite>How to Design Programs</cite></a>, Matthias Felleisen, Robert
 Bruce Findler, Matthew Flatt and Shriram Krishnamurthi, MIT Press,
 2001 (available in full on-line, date is for print version)
@@ -187,7 +187,7 @@ Felleisen, MIT Press, 1995
 <cite>Exploring Computer Science with Scheme</cite></a>, Oliver
 Grillmeyer, Springer-Verlag, 1998
 
-<li><a href="http://www.gustavus.edu/~max/concrete-abstractions.html">
+<li><a href="https://gustavus.edu/mcs/max/concrete-abstractions.html">
 <cite>Concrete Abstractions: An Introduction to Computer Science Using
 Scheme</cite></a>, Max Hailperin, Barbara Kaiser and Karl Knight, PWS
 Publishing, 1998
@@ -267,12 +267,12 @@ object of study or employ Scheme to illustrate key ideas.
 Daniel P. Friedman, William E. Byrd, and Oleg Kiselyov,
 MIT Press, 2005
 
-<li><a href="http://www.cs.indiana.edu/eopl/">
+<li><a href="https://cs.indiana.edu/eopl/">
 <cite>Essentials of Programming Languages</cite></a> (2/e), Daniel
 P. Friedman, Mitchell Wand and Christopher T. Haynes, MIT
 Press, 2001
 
-<li><a href="http://www.cs.brown.edu/~sk/Publications/Books/ProgLangs/">
+<li><a href="https://cs.brown.edu/~sk/Publications/Books/ProgLangs/">
 <cite>Programming Languages: Application and Interpretation</cite></a>,
 Shriram Krishnamurthi, 2003
 
@@ -329,7 +329,7 @@ repository at CMU</a> has an older one.
 
 <p>
 The archives of the <a
-href="http://www.swiss.ai.mit.edu/projects/scheme/rrrs-archive.html">
+href="https://groups.csail.mit.edu/mac/projects/scheme/rrrs-archive.html">
 RnRS authors' mailing list</a>, dating back to 1984, have recently
 become available on-line.
 </p>
diff --git a/www/Education/index.html b/www/Education/index.html
index a35fab9..fe7034a 100644
--- a/www/Education/index.html
+++ b/www/Education/index.html
@@ -63,7 +63,7 @@ primary languages:
 
 <ul>
 
-<li><a href="http://www.cs.indiana.edu/eip/home.html">
+<li><a href="https://www.cs.indiana.edu/eip/home.html">
 Indiana University</a>
 
 <li>
diff --git a/www/Events/index.html b/www/Events/index.html
index 0d7620e..dc9471c 100644
--- a/www/Events/index.html
+++ b/www/Events/index.html
@@ -40,19 +40,19 @@ has its own
 
 <li>
 The
-<a href="http://users.csc.calpoly.edu/~clements/scheme-workshop-2009/">2009
+<a href="http://www.schemeworkshop.org/2009/">2009
 Scheme workshop</a> was in Boston.
 </li>
 
 <li>
 ICFP 2008 featured the
-<a href="http://www.ccs.neu.edu/home/will/scheme2008/">Scheme 2008</a>
+<a href="http://www.schemeworkshop.org/2008/">Scheme 2008</a>
 workshop.
 </li>
 
 <li>
 ICFP 2007 featured the
-<a href="http://sfp2007.ift.ulaval.ca/">Scheme 2007</a>
+<a href="http://www.schemeworkshop.org/2007/">Scheme 2007</a>
 workshop.
 </li>
 
@@ -62,7 +62,7 @@ Scheme 2006</a> workshop.
 </p>
 
 <li>ICFP 2005 featured the
-<a href="http://www.deinprogramm.de/scheme-2005/">
+<a href="https://www.deinprogramm.de/scheme-2005/">
 Scheme 2005</a> workshop.
 </li>
 
@@ -72,20 +72,20 @@ Scheme 2005</a> workshop.
 </li>
 
 <li>Olin Shivers and Oscar Waddell chaired the
-<a href="http://www.cs.indiana.edu/scheme2004/">
+<a href="http://www.schemeworkshop.org/2004/">
 2004 Scheme Workshop</a> in Snowbird, Utah, in September, 2004.
 The workshop's Web site includes the proceedings.
 </li>
 
 <li>Pascal Costanza organized the
-<a href="http://www.cs.uni-bonn.de/~costanza/lisp-ecoop/">
+<a href="https://www.cs.uni-bonn.de/~costanza/lisp-ecoop/">
 First European Lisp and Scheme Workshop</a>
 in conjunction with ECOOP in Oslo in June, 2004.
 The workshop's Web site includes the proceedings.
 </li>
 
 <li>Matthew Flatt chaired the
-<a href="http://scheme2003.flux.utah.edu/">
+<a href="http://www.schemeworkshop.org/2003/">
 2003 Scheme Workshop</a> in Boston in November, 2002.
 Jay McCarthy took
 <a href="http://www.makeoutcity.com/Downloads/2003-SchemeWorkshop.html">
@@ -100,13 +100,13 @@ in October, 2002.  The workshop's Web site includes the proceedings.
 </li>
 
 <li>Manuel Serrano chaired
-<a href="http://kaolin.unice.fr/Scheme2001/">
+<a href="http://www.schemeworkshop.org/2001/">
 Scheme and Functional Programming, 2001</a> in Florence
 in September, 2001.  The workshop's Web site includes the proceedings.
 </li>
 
 <li>Matthias Felleisen organized a workshop,
-<a href="http://www.cs.rice.edu/~matthias/Scheme2000/">Scheme and
+<a href="http://www.schemeworkshop.org/2000/">Scheme and
 Functional Programming</a>, as part of
 <a
 href="http://www.cs.yorku.ca/pli-00/">Principles, Logics, and
@@ -117,7 +117,7 @@ September 2000.  The workshop's Web site includes the proceedings.
 <li> Richard Kelsey organized a
 Scheme
 Strawman Workshop in conjunction with the <a
-href="http://www.cs.rice.edu/Conferences/ICFP98/">International
+href="https://dblp.org/db/conf/icfp/icfp98.html">International
 Conference on Functional Programming</a> (ICFP '98) in September,
 1998.  The
 <a href="/Events/Workshops/Sep1998/minutes">minutes</a> are
diff --git a/www/Implementations/index.html b/www/Implementations/index.html
index 2f05a23..c125222 100644
--- a/www/Implementations/index.html
+++ b/www/Implementations/index.html
@@ -63,12 +63,12 @@ environments, including those listed below.
   <a href="http://www.schemers.com/3dscm1.html">3DScheme Pro</a> and
   <a href="http://www.schemers.com/edschem.html">EdScheme</a>
 <li> <a href="http://www-sop.inria.fr/mimosa/fp/Bigloo/">Bee</a>
-<li><a href="http://www.drscheme.org/">DrScheme</a>
+<li><a href="https://racket-lang.org/">DrScheme</a>
 <li><a href="http://www.pawfal.org/fluxus/">fluxus</a>,
   a livecoding environment
-<li><a href="http://schemeway.sourceforge.net/">SchemeWay</a>,
+<li><a href="https://sourceforge.net/projects/schemeway/">SchemeWay</a>,
  a Scheme environment built atop Eclipse</li>
-<li><a href="http://www.davidpilo.com/pvts/">Pilo Visual Tools
+<li><a href="https://www.davidpilo.com/pvts/">Pilo Visual Tools
  for Scheme</a></li>
 </ul>
 </p>
diff --git a/www/Miscellaneous/index.html b/www/Miscellaneous/index.html
index 3be8d06..1f8ca07 100644
--- a/www/Miscellaneous/index.html
+++ b/www/Miscellaneous/index.html
@@ -39,7 +39,7 @@ core dumps.  Here are some examples:
 
 <ol>
 
-<li> <a href="http://www.cs.rice.edu/~shriram/">Shriram
+<li> <a href="https://cs.brown.edu/~sk/">Shriram
 Krishnamurthi</a> wrote <a
 href="imagine.txt"><code>(Imagine)</code></a> to celebrate Scheme's
 twentieth birthday.
@@ -49,7 +49,7 @@ encountering Scheme in verse.
 
 <li> <a href="http://www.cs.washington.edu/homes/jbuhler/">Jeremy
 Buhler</a> contributed <a href="lispm-verse.txt">this bit</a> for the
-<a href="http://www.cs.rice.edu/~shriram/LispM/">Seasonal Lisp
+<a href="https://cs.brown.edu/research/plt/LispM/">Seasonal Lisp
 Machine</a>.
 
 </ol>
diff --git a/www/Other/index.html b/www/Other/index.html
index a84f531..2b42416 100644
--- a/www/Other/index.html
+++ b/www/Other/index.html
@@ -34,14 +34,14 @@ Other sources of information on Scheme include archives at:
 <ul>
 
 <li> <a
-href="http://legacy.cs.indiana.edu/scheme-repository/SRhome.html">Indiana</a>
+href="https://legacy.cs.indiana.edu/scheme-repository/SRhome.html">Indiana</a>
 
 <li> <a
 href="http://www.cs.cmu.edu/afs/cs.cmu.edu/project/ai-repository/ai/lang/scheme/0.html">Carnegie
 Mellon</a>
 
 <li> <a
-href="http://www.swiss.ai.mit.edu/projects/scheme/index.html">
+href="http://groups.csail.mit.edu/mac/projects/mac/">
 MIT's Scheme ``home page''</a>
 
 <li> <a href="http://www.ai.mit.edu/projects/su/su.html">MIT's Scheme
@@ -55,7 +55,7 @@ University of Technology</a>
 
 <p>
 The principal Scheme newsgroup is <a
-href="news:comp.lang.scheme"><code>comp.lang.scheme</code></a>.
+href="https://groups.google.com/g/comp.lang.scheme"><code>comp.lang.scheme</code></a>.
 </p>
 
 <p>
diff --git a/www/Positions/index.html b/www/Positions/index.html
index 86f1e05..dfbca87 100644
--- a/www/Positions/index.html
+++ b/www/Positions/index.html
@@ -31,7 +31,7 @@
 <p>
 Though this site does not endorse any particular commercial
 organization, we are enthusiastic about the existence of <a
-href="http://functionaljobs.com/">Functional Jobs</a>, which posts
+href="https://functionaljobs.com/">Functional Jobs</a>, which posts
 information about jobs that demand functional programmers.  Please
 take a look at their offerings.  (However, note that we have not
 vetted their content.)
diff --git a/www/Tutorials/index.html b/www/Tutorials/index.html
index 4a27e2a..3637e4b 100644
--- a/www/Tutorials/index.html
+++ b/www/Tutorials/index.html
@@ -32,7 +32,7 @@ There are many fine <a href="../Documents/#intro-texts">introductory
 textbooks</a> from which you can learn the principles and pragmatics
 of programming in Scheme.  If you're looking for a Web-based tutorial,
 we recommend <a
-href="http://www.htdp.org/"><cite>How
+href="https://htdp.org/"><cite>How
 to Design Programs</cite></a> published by MIT Press.
 
   </td>
diff --git a/www/Welcome/index.html b/www/Welcome/index.html
index afaae90..d9b3b59 100644
--- a/www/Welcome/index.html
+++ b/www/Welcome/index.html
@@ -31,16 +31,16 @@
 <p>
 Welcome to schemers.org!  This is a collection of resources for the
 Scheme programming language.  It was initiated by the
-<a href="http://www.plt-scheme.org/">PLT</a> group at
+<a href="https://www.cs.rice.edu/CS/PLT/">PLT</a> group at
 Rice University.
 It now runs on a server in the
-<a href="http://www.cs.brown.edu/">Brown University computer
+<a href="https://www.cs.brown.edu/">Brown University computer
 science department</a>.
 </p>
 
 <p>
 The pages were built and are maintained by <a
-href="http://www.cs.brown.edu/~sk/">Shriram Krishnamurthi</a>,
+href="https://www.cs.brown.edu/~sk/">Shriram Krishnamurthi</a>,
 with help from other members of Rice PLT, most notably
 Matthias Felleisen,
 Paul Steckler and
diff --git a/www/index.html b/www/index.html
index 2f7e49c..6225029 100644
--- a/www/index.html
+++ b/www/index.html
@@ -76,7 +76,7 @@ and
 
 <p>
 Manuel Serrano was invited to give a seminar on Hop to
-<a href="http://www.youtube.com/watch?v=i7bc6yiJQ0I">the
+<a href="https://www.youtube.com/watch?v=i7bc6yiJQ0I">the
 Coll&egrave;ge de France</a>.
 </p>
 
@@ -97,7 +97,7 @@ You can also find some articles
 </p>
 
 <p>
-Check out the Scheme <a href="http://scheme.meetup.com/">Meetup site</a>.
+Check out the Scheme <a href="https://scheme.meetup.com/">Meetup site</a>.
 </p>
 
 <p align="CENTER">
@@ -124,15 +124,15 @@ Check out the Scheme <a href="http://scheme.meetup.com/">Meetup site</a>.
    (<font color=PURPLE>choose-from</font> <a href="http://community.schemewiki.org/?scheme-faq-standards#implementations">implementations</a>
                 <a href="http://community.schemewiki.org/?scheme-faq-standards#libraries">libraries</a>
                 <a href="Implementations/#environments">environments</a>
-                <a href="http://srfi.schemers.org/">Reqests for Implementation</a> (<a href="https://srfi.schemers.org/srfi.svg">SRFI</a>)))
+                <a href="https://srfi.schemers.org/">Reqests for Implementation</a> (<a href="https://srfi.schemers.org/srfi.svg">SRFI</a>)))
   ((<font color=GREEN>socialize</font>)
    (<font color=PURPLE>choose-from</font> <a href="http://www.hpc.unm.edu/~download/abqlispscheme/">ABQ Lisp/Scheme</a> - Albuquerque, NM, USA
                 <a href="http://balisp.org/">Bay Area Lisp &amp; Scheme</a> - Bay Area, CA, USA (<a href="http://balisp.org/videos">videos<a>)
-                <a href="http://www.neilvandyke.org/boston-lisp-announce/">Boston Lisp Announce</a> - Boston, MA, USA
-                <a href="http://schematics.sourceforge.net/scheme-uk/">Scheme UK</a> - London, UK
+                <a href="https://www.neilvandyke.org/boston-lisp-announce/">Boston Lisp Announce</a> - Boston, MA, USA
+                <a href="https://schematics.sourceforge.net/scheme-uk/">Scheme UK</a> - London, UK
                 <a href="http://community.schemewiki.org/?munich-lisp">munich-lisp</a> - Munich, Germany
                 <a href="http://cracl.wordpress.com/">CRACL</a> - Los Angeles, CA, USA
-                <a href="http://metalab.at/wiki/Lambdaheads">Lambdaheads</a> - Vienna, Austria
+                <a href="https://metalab.at/wiki/Lambdaheads">Lambdaheads</a> - Vienna, Austria
                 <a href="http://www.lisperati.com/fringedc.html">FringeDC</a> - Washington, DC, USA))
   ((<font color=GREEN>work</font>)
    (<font color=PURPLE>choose-from</font> <a href="Positions/">jobs</a>))