Strugatsky, Arkady and Boris. The Ugly Swans. New York, Macmillan

Strugatsky, Arkady and Boris. The Ugly Swans. New York, Macmillan, Box: 25, Folder: 1. Papers of Theodore Sturgeon, MS 254. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/244133 Accessed December 25, 2025.