^"As a conjecture some scholars locate the life-span of Euclid between 435 and 365 BCE." Giovanni Reale, John R. Catan, (1987), A History of Ancient Philosophy, page 373. SUNY Press
^Diogenes Laërtius, ii. 106; Cicero, Academica, ii. 42; Aulus Gellius, vii. 10. 1-4; Plato, Phaedo, 59B-C; Strabo, ix. 1. 8; although, according to Diogenes Laërtius, others called him a native "of Gela, as Alexander states in his Successions of Philosophers"