The many older books can be located in second-hand book stores, reference libraries via ILL (Inter-Library Loan), or by book finders. Of course, you know to read magazines and newspapers of the time to pick up the period flavour and concerns. For costume, avoid most books: they often lump "the Forties" together, though there were two fashion periods, the shoulder pads, high hem, late-Thirties-like fashions of the first half, and the purposely revolutionary, corsetted, narrow-shouldered, long, full-skirted New Look from Dior after the War. Best to read back issues of the fashion magazines of the period. Be sure and catch the Atlas of Civilisation series, in this case the WWII chapters of The Cultural Atlas of France, The Cultural Atlas of Russia, etc.
American Red Cross
Angelucci, Enzo, & Paolo Maricardi
Boardman, Barrington
Braun, Werner von, and Frederick I. Ordway III
Chapman, Charles Frederic
Churchill, Sir Winston
Cormack, Alexander J.R., editor, with Mjr. F. W. A. Hobart and Lt. Col. John Weeks
Cornell, James
Costello, JohnVirtue
Davis, Larry
Deacon, Richard
Donhoff, Marion, countess
Duffy, James P., and Vincent L. Ricci
Dupuy, Trevor Nevitt, Col. US Army, ret.
Ehrlich, Blake
Ford, Brian
Fourtouni, Eleni
Hadjipateras, C. N.
Hatcher, Julian S., Maj. Gen., US Army, ret.
Heiden, Konrad
Heiferman, Ronald
Hibbert, Christopher
Hingley, Ronald
Hogg, Ian V.
Ingraham, Holly
Keegan, John, ed.
Kennedy, Ludovic
Lee, Eric C. B. & Kenneth
Lincoln, John Ware
Macksey, Kenneth & John H. Batchelor
Mauldin, Bill
Mazower, Michael
Melton, H. Keith
The Military Service Publishing Company
Miller, Nathan
Nock, O .S., editor
"Old Sarge"
O'Leary, Michael
Perrault, Gilles
Rawicz, Slavomir, as told to Ronald Downing
Reider, Frederic
Rowland, K. T.
Salmonson, Jessica Amanda
de Seversky, Maj. Alexander P.
Shiber, Etta, with Anne and Paul Dupre
Simonds, Frank H., Litt.D., & Brooks Emeny, PhD
Singer, Kurt
Sklar, Dusty
Smith, J. R., and Antony L. Kay
Sparks, Nancy J., editor
Time Life Books, the editors of
Valant, Gary M.
Vanderveen, Bart H., editor; compiled by the Olyslager Organization
Ventry, Arthur F. D. E., baron, and Eugene M. Koesnik
Wall, Robert
Willmott, H. P.
Wood, Tony, and Bill Gunston
editors of the New York *World*
There's some astonishing stuff out there, from aircraft training films to deathcamp footage "For Adults Only." This a sample of items to get you grounded.
B-25/B-26 ****
Fight for the Sky - P47/P-47 Operations ****
Flying the B-17 ****
P-40/P-38 ****
Great Battles of World War II: North Africa/Western Europe ****
Victory At Sea ****
The "Why We Fight Series" *****!
http://www.ucr.edu/h-gig/topperindex.html
A thorough-going linksite maintained by the University of California at Riverside, H-GIG sorts by area, by era (ancient, Medieval, early Modern, Modern, and 20th C<yours>), or by topic (military, women, etc.). It's a good place to start a hunt for books and essays online.