I would be interested in knowing how he obtained such detailed records given how most USAFFE records were destroyed in '41-'42.
He has a very interesting section on sources.
One is an extensive set of debrief interviews conducted by the USAF postwar with the survivors.
Another is the USAFFE records that were flown out in April 1942 and turned up in the McArthur papers in 1960. So a great number of USAFFE records apparently survived, G-2, G-3 and S-3 records, along with the FEAF War Diary.
Besides this he seems to have conducted an extensive set of additional interviews with survivors and their relatives, starting in the 1970’s, also obtaining their wartime and postwar correspondence.
Its a very interesting book.