Here are copies of various interesting pages that I have linked to. Unfortunately, the internet is designed in such a way that the original can disappear without a trace. To prevent this from happening, I keep copies of the very best material on my server. Since I make regular backups (and recommend that you do too), one can hope that my copies will outlive some of the originals.
Of course, all rights to the materials belong to their owners, but since I am a proponent of extremely moderate copyright, they will remain here until the owners firmly ask me to remove them.