Set of 4 WWII Aircraft Identification "Friend or Foe?" Booklets - 1940/41

Four booklets prepared by Aeroplane magazine, each 8 x 5.5" as follows: Part 1, British and German Fighters and Bombers, 64 pages; Part 2, British and German Troop Carriers and Seaplanes/British Trainers, 64 pages; Part 3, Italian Fighters, Bombers and Seaplanes, 64 pages; Part 4, American Types for the RAF, 62 pages.  In each volume, an aircraft has a two-page spread with 5-view silhouettes and specs on the left page and multiple b&w photos on the right page. All very good in mylar.