Fix broken external links in documentation

* doc/gcdescr.html: Replace broken URLs to external document with
working ones.
* doc/overview.html: Likewise.

2 files changed, 11 insertions, 11 deletions

diff --git a/doc/gcdescr.html b/doc/gcdescr.html
index 294e40a6..1605af43 100644
--- a/doc/gcdescr.html
+++ b/doc/gcdescr.html
@@ -488,9 +488,9 @@ the vast majority of objects use <TT>GC_malloc_stubborn</tt>.
 
 The collector implements <I>black-listing</i> of pages, as described
 in
-<A HREF="http://www.acm.org/pubs/citations/proceedings/pldi/155090/p197-boehm/">
+<A HREF="http://dl.acm.org/citation.cfm?doid=155090.155109">
 Boehm, ``Space Efficient Conservative Collection'', PLDI '93</a>, also available
-<A HREF="papers/pldi93.ps.Z">here</a>.
+<A HREF="https://www.cs.rice.edu/~javaplt/311/Readings/pldi93.pdf">here</a>.
 <P>
 During the mark phase, the collector tracks ``near misses'', i.e. attempts
 to follow a ``pointer'' to just outside the garbage-collected heap, or
diff --git a/doc/overview.html b/doc/overview.html
index 394e5ba5..4ca2f3ef 100644
--- a/doc/overview.html
+++ b/doc/overview.html
@@ -27,10 +27,9 @@
 before that at
 <tt>http://reality.sgi.com/boehm/gc.html</tt>
 and before that at
-<a href="ftp://ftp.parc.xerox.com/pub/gc/gc.html">
-<tt>ftp://ftp.parc.xerox.com/pub/gc/gc.html</tt></a>. ]
+<tt>ftp://ftp.parc.xerox.com/pub/gc/gc.html</tt>. ]
 <p>
-The <a href="http://www.hboehm.info">Boehm</a>-<a href="http://www.cs.cornell.edu/annual_report/00-01/bios.htm#demers">Demers</a>-<a href="http://www-sul.stanford.edu/weiser/">Weiser</a>
+The <a href="http://www.hboehm.info">Boehm</a>-<a href="http://www.cs.cornell.edu/annual_report/00-01/bios.htm#demers">Demers</a>-<a href="http://www.ubiq.com/hypertext/weiser/weiser.html">Weiser</a>
 conservative garbage collector can
 be used as a garbage collecting
 replacement for C <tt>malloc</tt> or C++ <tt>new</tt>.
@@ -68,7 +67,7 @@ included as part of the
 <a href="http://gcc.gnu.org/">GNU compiler</a>
 distribution.  The source
 code for that version is available for browsing
-<a href="http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/boehm-gc/">here</a>.
+<a href="https://github.com/gcc-mirror/gcc/tree/gcc-6-branch/boehm-gc">here</a>.
 </p><p>
 The arguments for and against conservative garbage collection
 in C and C++ are briefly
@@ -110,8 +109,7 @@ HP/UX 11 pthreads, Tru64 pthreads, and MacOS X threads are supported
 in recent versions.
 </p><h3>Separately distributed ports</h3>
 For MacOS 9/Classic use, Patrick Beard's latest port is available from
-<a href="http://homepage.mac.com/pcbeard/gc/">
-<tt>http://homepage.mac.com/pcbeard/gc/</tt></a>.
+<tt>http://homepage.mac.com/pcbeard/gc/</tt>.
 (Unfortunately, that's now quite dated.
 I'm not in a position to test under MacOS.  Although I try to
 incorporate changes, it is impossible for
@@ -124,7 +122,7 @@ Precompiled versions of the collector for NetBSD are available
 versions of the collector.
 </p><h2><a name="multiprocessors">Scalable multiprocessor versions</a></h2>
 Kenjiro Taura, Toshio Endo, and Akinori Yonezawa have made available
-a <a href="http://web.yl.is.s.u-tokyo.ac.jp/gc/">parallel collector</a>
+a <a href="http://ieeexplore.ieee.org/abstract/document/1592629/">parallel collector</a>
 based on this one.  Their collector takes advantage of multiple processors
 during a collection.  Starting with collector version 6.0alpha1
 we also do this, though with more modest processor scalability goals.
@@ -275,7 +273,9 @@ using programs written for malloc/free.
 </p><p>
 Joel Bartlett's <a href="ftp://gatekeeper.dec.com/pub/compaq/WRL/research-reports/WRL-TN-12.ps">mostly copying conservative garbage collector for C++</a>.
 </p><p>
-John Ellis and David Detlef's <a href="ftp://ftp.parc.xerox.com/pub/ellis/gc/gc.ps">Safe Efficient Garbage Collection for C++</a> proposal.
+John Ellis and David Detlef's
+<a href="http://dl.acm.org/citation.cfm?id=1267983">Safe Efficient Garbage Collection for C++</a>
+proposal.
 </p><p>
 Henry Baker's <a href="http://home.pipeline.com/%7Ehbaker1/">paper collection</a>.
 </p><p>
@@ -335,7 +335,7 @@ research in algebraic geometry and commutative algebra.
 The <a href="http://www.vestasys.org/">Vesta</a> configuration management
 system.
 </p><p>
-<a href="http://www.visual-prolog.com/vip6">Visual Prolog 6</a>.
+<a href="http://www.visual-prolog.com/">Visual Prolog 6</a>.
 </p><p>
 <a href="http://asymptote.sf.net/">Asymptote LaTeX-compatible
 vector graphics language.</a>