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Mikhail, Devi︠a︡taev (2015). Pobeg iz ada: Na samolete vraga iz nemet︠s︡ko-fashistskogo plena (in Russian). Moscow, Russia: Moskva : Obshchestvo sokhranenii︠a︡ literaturnogo nasledii︠a︡. ISBN978-5-902484-72-1. LCCN2016454013.
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D'Olier, Franklin; Alexander; Ball; Bowman; Galbraith; Likert; McNamee; Nitze; Russell; Searls; Wright (September 30, 1945). "The Secondary Campaigns". United States Strategic Bombing Survey, Summary Report (European War). Archived from the original on 2008-05-16. Retrieved 2008-09-22. (Alternate version) (cited by Mets p. 239, which has the "three or four" numbers)
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D'Olier, Franklin; Alexander; Ball; Bowman; Galbraith; Likert; McNamee; Nitze; Russell; Searls; Wright (September 30, 1945). "The Secondary Campaigns". United States Strategic Bombing Survey, Summary Report (European War). Archived from the original on 2008-05-16. Retrieved 2008-09-22. (Alternate version) (cited by Mets p. 239, which has the "three or four" numbers)