Yahoo obituary.
http://movies.yahoo.com/news/movie-sword-fight-master-bob-anderson-dies-89-122704485.html
Kudos to Mark Hamill for giving Mr. Anderson public credit for his contributions to Empire and Jedi back when Lucasfilm was mum about such things.
In case you've never seen the specially modified Vader helmet Anderson wore on Empire up close...
http://www.starwarshelmets.com/Original-Darth-Vader-Helmets.htm
It's about halfway down the page.