From April 1928 to October 1929, Seidemann was trained as a Luftwaffe pilot at the secret training facility in Lipetsk, Soviet Union. He also participated in the third and fourth FAI International Tourist Plane Contest Challenge 1932 (7th place) and Challenge 1934 (3rd place).
By the mid 1930s Seidemann was a renowned air racer and won the 1937 London - Isle of Man Air Race.[1]
Fellgiebel, Walther-Peer (2000) [1986]. Die Träger des Ritterkreuzes des Eisernen Kreuzes 1939–1945 — Die Inhaber der höchsten Auszeichnung des Zweiten Weltkrieges aller Wehrmachtteile [The Bearers of the Knight's Cross of the Iron Cross 1939–1945 — The Owners of the Highest Award of the Second World War of all Wehrmacht Branches] (in German). Friedberg, Germany: Podzun-Pallas. ISBN978-3-7909-0284-6.
Thomas, Franz (1998). Die Eichenlaubträger 1939–1945 Band 2: L–Z [The Oak Leaves Bearers 1939–1945 Volume 2: L–Z] (in German). Osnabrück, Germany: Biblio-Verlag. ISBN978-3-7648-2300-9.