Ljunggren, Wilhelm. β€œOn an Improvement of a Theorem of T. Nagell Concerning the Diophantine Equation $Ax^3 + By^3 = C$”. Mathematica Scandinavica 1 (December 1, 1953): 297–309. Accessed September 8, 2026. https://journals.msp.org/mscand/article/view/2935.