[wireandpaper]

Little by little I was gathering documentation wherever I visited: in discount bookstores (gone by the beginning of this century), used books stores (also almost gone and who knows with the pandemia) and ordering via by Amazon. Also I received the very nice book in Spanish by my brother, a good recount of all the fronts (originally in English).
War in the Air has excellent aerial photos of planes, balloons, and dirigibles flying.

Nevertheless, my favorite references are in the previous post!

ps: now we have internet!