Abramov, Vyacheslav, M. (21 June 2021). "A simple proof of Tong's theorem". arXiv:2106.13808 [math.HO].{{cite arXiv}}: CS1 maint: multiple names: authors list (link)
doi.org
Tong, Jingcheng (May 1994). "Kummer's Test Gives Characterizations for Convergence or Divergence of all Positive Series". The American Mathematical Monthly. 101 (5): 450–452. doi:10.2307/2974907. JSTOR2974907.
Tong, Jingcheng (May 1994). "Kummer's Test Gives Characterizations for Convergence or Divergence of all Positive Series". The American Mathematical Monthly. 101 (5): 450–452. doi:10.2307/2974907. JSTOR2974907.
Samelson, Hans (November 1995). "More on Kummer's Test". The American Mathematical Monthly. 102 (9): 817–818. doi:10.2307/2974510. JSTOR2974510.
projecteuclid.org
Frink, Orrin (October 1948). "A ratio test". Bulletin of the American Mathematical Society. 54 (10): 953–953.
Ďuriš, František (2009). Infinite series: Convergence tests (Bachelor's thesis). Katedra Informatiky, Fakulta Matematiky, Fyziky a Informatiky, Univerzita Komenského, Bratislava. Retrieved 28 November 2018.