Deruluft
Deruluft (Deutsch-Russische Luftverkehrs A.G., or Deruluft) was a joint German-Soviet airline, established on 11 November 1921. Deruluft opened its first permanent airlink between Moscow and Königsberg (via Kaunas and Smolensk) on 1 May 1922. It started a new route between Berlin and Leningrad (via Tallinn) on 6 June 1928, and maintained both routes until 31 March 1936. Deruluft was a successful business, but terminated on 31 March 1937 due to the changed political situation.