<h2>1.6 Are there other open-source implementations of OpenGL?</h2>
<p>
-Yes, SGI's <a href="http://oss.sgi.com/projects/ogl-sample/index.html">
+Yes, SGI's <a href="http://web.archive.org/web/20171010115110_/http://oss.sgi.com/projects/ogl-sample/index.html">
OpenGL Sample Implementation (SI)</a> is available.
The SI was written during the time that OpenGL was originally designed.
Unfortunately, development of the SI has stagnated.
an open-source implementation of OpenGL ES for mobile devices.
<p>
-<a href="http://www.dsbox.com/minigl.html">miniGL</a>
-is a subset of OpenGL for PalmOS devices.
+<a href="http://web.archive.org/web/20130830162848/http://www.dsbox.com/minigl.html">miniGL</a>
+is a subset of OpenGL for PalmOS devices. The website is gone, but the source
+code can still be found on <a href="https://sourceforge.net/projects/minigl/">sourceforge.net</a>.
<p>
<a href="http://bellard.org/TinyGL/">TinyGL</a>
<h3>2.4 Where is the GLw library?</h3>
<p>
-GLw (OpenGL widget library) is now available from a separate <a href="https://cgit.freedesktop.org/mesa/glw/">git repository</a>. Unless you're using very old Xt/Motif applications with OpenGL, you shouldn't need it.
+GLw (OpenGL widget library) is now available from a separate <a href="https://gitlab.freedesktop.org/mesa/glw">git repository</a>. Unless you're using very old Xt/Motif applications with OpenGL, you shouldn't need it.
</p>
<h2>2.5 What's the proper place for the libraries and headers?</h2>
<p>
On Linux-based systems you'll want to follow the
-<a href="http://oss.sgi.com/projects/ogl-sample/ABI/index.html">Linux ABI</a> standard.
+<a href="https://www.khronos.org/registry/OpenGL/ABI/">Linux ABI</a> standard.
Basically you'll want the following:
</p>
<dl>
<p>
Make sure the ratio of the far to near clipping planes isn't too great.
Look
-<a href="https://www.opengl.org/resources/faq/technical/depthbuffer.htm#0040">here</a>
+<a href="https://www.opengl.org/archives/resources/faq/technical/depthbuffer.htm#0040">here</a>
for details.
</p>
<p>