Friedrichshafen FF.21 explained

The Friedrichshafen FF.21 was a German multirole flying boat of the 1910s produced by Flugzeugbau Friedrichshafen.

Bibliography

• Book: Herris . Jack . Friedrichshafen Aircraft of WWI: A Centennial Perspective on Great War Airplanes . 2016 . Aeronaut Books . Charleston, South Carolina . 978-1-935881-35-3. Great War Aviation Centennial Series. 21.

Further reading

• Book: Kober . Theodor von . Borzutzki . Siegfried . Flugzeugbau Friedrichshafen GmbH : Diplom-Ingenieur Theodor Kober . 1993 . limited . Burbach . 978-3927513600 . 1. Aufl . German . 98-99.