Iqanda (0) yinombolo eyehlukile. Le-athikhili iyisigcino (isiNgisi: "a stub"). Ungakwazi ukusiza uWikipedia: ngokuyikhulisa. Russell, Bertrand (1942). Principles of mathematics (2 ed.). Forgotten Books. p. 125. ISBN 1-4400-5416-9., Chapter 14, page 125