From: R. Stricklin
I saved a copy in 2012. ... Grab them while you still
can.
The tendency of links to go bad is momumental; the probability of it
happening over long time periods seems to asymtotically approach 1.0.
So everyone ought to make a habit of down-loading a copy of anything they
have an interest in; the existence of multiple copies seems to be the best
safeguard that material will not be lost.
Noel