The XA-39 is covered in American Secret Projects, 1937-1945, authored by Tony Buttler and Alan Griffith and to be published by Ian Allan later this year. Not only are additional photos of the mockup provided but a new 3-view based on the original factory General Arrangement 3-view is included, plus dimensions, performance figures, etc., all from original USAAF and Kaiser-Fleetwings files.
Roughly, the book contains approximately 80,000 words, 135 -3-views (with at least 78 being brand new based on original drawings), and photos number between 250-300. These are rough figures as the editing process can change them.
As with all of Tony's books, you will find many, many, many designs you've never heard of. Fortunately, he and I have both been independently researching this stuff for many years, and my numerous trips to various Archives across the U.S. have provided a gold mine of data, plus help from many of the best and most generous researchers and archivists you could possibly ask for. Not only that, but Tony and I have independently identified the one or two researchers who are a total pain in the rear and won't share anything! It has, indeed, been a voyage of discovery for both and certainly a new-found friend for me.
Film at 11!
Alang