For anyone interested in the Philips Stirling research this is an extremely worthwhile read, and although its stated as only a google books preview,
it is fairly comprehensive and seems to contain most of the significant information from within the book regarding Stirling engines (section 6.1) minus a few images...
It's more an overview of the Stirling's evolution at Philips than it is a technical explanation of the engine.
There's about 12 pages on their stirling engine research..

http://books.google.com.au/books?id=Mf1 ... &q&f=false
vamoose