Euclidean and Non-Euclidean Geometries, pp. 211–3, W.H. Freeman & Company. Gowers, T. and Barrow-Green, J. and Leader, I. The Princeton Companion to Mathematics
reason at all to omit zero from the pattern." Caldwell & Xiong 2012,第5–6頁. Gowers 2002,第118頁 "The seemingly arbitrary exclusion of 1 from the definition of