Bugeaud, Y. and Mihailescu, P. 2007. On the Nagell-Ljunggren equation $(x^n - 1)/(x - 1) = y^q$. MATHEMATICA SCANDINAVICA. 101, 2 (Dec. 2007), 177–183. DOI:https://doi.org/10.7146/math.scand.a-15038.