Filtering by: File Format video/mp4 Remove constraint File Format: video/mp4 Resource Type moving image Remove constraint Resource Type: moving image Subject antarctica--aerial exploration Remove constraint Subject: antarctica--aerial exploration Subject airplanes Remove constraint Subject: airplanes Subject scientific expeditions Remove constraint Subject: scientific expeditions Time Period (Topic) 1920s (1920-1929) Remove constraint Time Period (Topic): 1920s (1920-1929)