I have a few sources
-Angelucci's collection
-The Complete Book of Fighters-William Green and Gordon Swanborough
-The Encyclopaedia of World Aircraft-Paul Eden and Soph Moeng
-Osprey Encyclopaedia of Russian Aircraft-Bill Gunston
-Aircraft of the Fighting Powers(War time publication, so not always accurate but all drawings in large size) Volumes 1,2,3 and 6
etc. I don't want to boast but I have 2 walls of my living room covered in bookshelves and half of that is on airplanes, and still have half of my library in boxes in the attic waiting for permission from my missis to convert a good portion of the ground floor in library.......or moving to a larger house!!!!
Most of the aviation books are on Luftwaffe subjects and other air forces, and just a couple on comercial a/c. Many modelling magazines, Air Enthusiast, Squadron, Profiles, and a bunch of old Airfix Magazine from the 60's and 70's. I have suscription to Tankette (general interest on armour with many drawings), TNT and Histoire de Guerre-Blindes et Materiels (this last two are in french on armor also)
The rest of the library is Uniforms, AFV, Word War One, Ships, Cars and some militaria.
Also have a big display unit (second hand from a previous Cristal Shop) full with Plastic and paper models at 1/72nd scale and also 1/72nd Diecast cars and 54mm lead figures. Very bad thing having such a broad interest, as I don't yet know if I will ever display my B-52 and C-135!!!
That has prevented me from building a lot of planes lately, as 1/72 scale tanks and vehicles use a lot less space!!!!.
Any obscure planes give me a boost to dig into my pile of reference, as long as they get some historical background, so any one needing info just let me know.
Panzerbeto