How to select the proper glow plug

The 1963 American Modeler Annual contained an article by Bill Netzeband entitled 'How to select the proper glow plug'. I have added this to the historic C/L articles on my website. Although the plug information is mainly out of date, it's a very useful article. Here's the direct link:
http://www.iroquois.free-online.co.uk/gloplug.htm
If you read this Bill, take this as my tribute to all your fine work.