Hagis, Peter Jr.; McDaniel, Wayne L. (1972). “A new result concerning the structure of odd perfect numbers”. 《Proceedings of the American Mathematical Society》 32 (1): 13–15. doi:10.1090/S0002-9939-1972-0292740-5. ISSN1088-6826. MR0292740.
Zelinsky, Joshua (July 2019). “Upper bounds on the second largest prime factor of an odd perfect number”. 《International Journal of Number Theory》 15 (6): 1183–1189. arXiv:1810.11734. doi:10.1142/S1793042119500659. S2CID62885986..
Konyagin, Sergei; Acquaah, Peter (2012). “On Prime Factors of Odd Perfect Numbers”. 《International Journal of Number Theory》 8 (6): 1537–1540. doi:10.1142/S1793042112500935.
Zelinsky, Joshua (July 2019). “Upper bounds on the second largest prime factor of an odd perfect number”. 《International Journal of Number Theory》 15 (6): 1183–1189. arXiv:1810.11734. doi:10.1142/S1793042119500659. S2CID62885986..
Hagis, Peter Jr.; McDaniel, Wayne L. (1972). “A new result concerning the structure of odd perfect numbers”. 《Proceedings of the American Mathematical Society》 32 (1): 13–15. doi:10.1090/S0002-9939-1972-0292740-5. ISSN1088-6826. MR0292740.
Kühnel, Ullrich (1950). “Verschärfung der notwendigen Bedingungen für die Existenz von ungeraden vollkommenen Zahlen”. 《Mathematische Zeitschrift》 (독일어) 52: 202–211. doi:10.1007/BF02230691. S2CID120754476.
Zelinsky, Joshua (July 2019). “Upper bounds on the second largest prime factor of an odd perfect number”. 《International Journal of Number Theory》 15 (6): 1183–1189. arXiv:1810.11734. doi:10.1142/S1793042119500659. S2CID62885986..
Hagis, Peter Jr.; McDaniel, Wayne L. (1972). “A new result concerning the structure of odd perfect numbers”. 《Proceedings of the American Mathematical Society》 32 (1): 13–15. doi:10.1090/S0002-9939-1972-0292740-5. ISSN1088-6826. MR0292740.