For who have interest in old books about the Great War, you can take a look here. (When already post, my excuse, I good not find it)
https://archive.org/details/texts Just fill in the title and you can download it for free and it is legal.
There is a lot more, just try names etc.
Here some titles about aviation of the Great War.
Dictionary of Aviation (1911)
Field Notes From the Russian Front (1915)
Flying for France. With the American Escadrille at Verdun (1918)
Flying Machines Today (1911)
Flying Machines. Construction and Operation (1910)
Flying Machines. Past, Present & Future (±1907)
Flying Men & Their Machines (1916)
Flying-Machines. Past, Present & Future. 3rd ed. (±1914?)
German Plans for the Next War (1918) BIZAR!! 1918 en de nieuwe oorlog reeds voorspeld!!
Guide for the .303-in. Vickers Machine Gun (1915)
Handbook of Aircraft Armament (1918)
Practical Flying. Complete Course of Flying Instruction [Temple, 1918]
Stability in Aviation. An Introduction to Dynamical Stability as applied to the Motions of Aeroplanes (1911)
Textbook of Applied Aeronautic Engineering (1920)
The Airplane Engine (1922)
The Flying Ace (1917)
The Flying Spy (1919)
With the French Flying Corps [Charles Scribner's] (1917)
The Lafayette Flying Corps. Volume 1 (1920)
With The Flying Squadron. Being the War Letters of the late Harold Rosher to his family (1916)
With the French Flying Corps (1917)
Aeroplanes [Cupples & Leon, 1915]
Speeches of The Flying Squadron [Hanly & Stewart, 1915?)
Aerial Observation. The Airplane observer, the balloon observer and the Army Corps Pilot [Harper, 1921]
Aeroplanes [Cupples & Leon] (1915)
Air Forces of the Baltic States. Lithuania, Estonia, Latvia, Middle Lithuania 1920-1921 [Blue Rider]
Aircraft and Submarines. The Story of the Invention, Development, and Present-Day Uses of War's Newest Weapons [Putnam, 1918]
Aircraft in War [MacMillan, 1914]
Aviation Engines (1919)
Aviation in Canada 1917-1918 (1919)
Bibliography of Aeronautics [Smithsonian] (1919)
Dictionary of Aviation [Baker & Taylor, 1911]
Harper's Aircraft Book [Harper, 1913]
Harper's Aircraft Book. Why Aeroplanes fly, how to make models, and all about aircraft, little and big (1913)
Heroes of Aviation [Little, Brown, and Co., 1919]
Manual of Military Aviation (1917)
Natural Stability and The Parachute Principle in Aeroplanes [Spon] (1911)
Plane Tales from the Skies [Cassell, 1918]
Practical Aviation including Construction and Operation [Wireless Press] (1918)
Provisional Description of Italian Observation Balloon (1919)
R.F.C. H.Q. 1914-1918 [G. Bell] (1920)
Sixty Squadron R.A.F. A History of the Squadron from its formation [Heinemann, 1920]
Sky High. The Story of Aviation [Little, Brown] (1930)
Tails Up (1918)
The Aeroplane. A Concise Scientific Study (1915)
The Big Aviation Book for Boys [McLoughlin] (1929)
The Complete Airman [Methuen, 1920]
The Curtiss Aviation Book [Frederick A. Stokes Company, 1912]
The Prehistory of Aviation [Field Museum of Natural History] (1928)
War Flying [Houghton Mifflin] (1917)
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Also look here:
Here a fine collection of Ameri...cana?

4 volumes and also in EPUB.
https://archive.org/...tion:opensource And more titles, just experiment with words and you be amassed what you can find:
https://archive.org/...ial operations"
or
http://www.digitalbo...ryaviationa.asp
PS: Nothing feels (well almost ;- ) so good as a real book!