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Leuschner, Armin Otto. The Astronomical Romance of Pluto. Publications of the Astronomical Society of the Pacific. 1932, 44: 197–214. Bibcode:1932PASP...44..197L. doi:10.1086/124230.
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Joe Tenn. 1936 Bruce Medalist. Sonoma State University. [2010-01-20]. (原始内容存档于2021-04-22).
J. K. Davies; J. McFarland; M. E. Bailey; B. G. Marsden; W. I. Ip. The Early Development of Ideas Concerning the Transneptunian Region. M. Antonietta Baracci; Hermann Boenhardt; Dale Cruikchank; Alissandro Morbidelli (编). The Solar System Beyond Neptune(PDF). University of Arizona Press. 2008: 11–23. (原始内容(PDF)存档于2015年2月20日).
Joe Tenn. 1936 Bruce Medalist. Sonoma State University. [2010-01-20]. (原始内容存档于2021-04-22).