The Pfalz Dr.II was a lightweight development of the Dr.I with a reduced wing area. The first prototype had a 110 hp (81 kW) Oberursel Ur II engine, and the second prototype (Dr.IIa) used a Siemens-Halske Sh I engine, which developed the same power. However, the Dr.II did not enter production.[1][2]
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Enzo Angelucci (1981). Rand McNally Encyclopedia of Military Aircraft, 1914-1980. Crescent. ISBN978-0-517-41021-9.
William Green; Gordon Swanborough (1998-12-01). Complete Book of Fighters. ISBN978-1-85833-777-7.
Herris, Jack (2012). Pfalz Aircraft of WWI: A Centennial Perspective on Great War Airplanes. Great War Aviation Centennial Series. Vol. 5. Charleston, SC: Aeronaut Books. ISBN978-1-935881-12-4.