Filtering by: Resource Type moving image Remove constraint Resource Type: moving image Subject airplanes Remove constraint Subject: airplanes Subject scientific expeditions Remove constraint Subject: scientific expeditions Time Period (Topic) 1930s (1930-1939) Remove constraint Time Period (Topic): 1930s (1930-1939) Time Period (Topic) 1920s (1920-1929) Remove constraint Time Period (Topic): 1920s (1920-1929)