As we all know, links come and go. I do occasionally check the validity of the links on my website. However, if you discover before I do that a link isn't working, please drop me a line and I'll remove it.
If you would like a link to your page from my website, let me know. I will add the link in the most appropriate place, not necessarily on this page. I'll add links to all non-commercial organisations. Commercial organisations will be added if they contribute some sort of useful knowledge.