^This is the date given by V. F. Kagan's 1957 book N. Lobachevsky and His Contribution to Science (first published in Russian in 1943), p. 26, and A. A. Andronov's 1956 article "Где и когда родился Н.И.Лобачевский" ("Where and when was Lobachevsky born?") (the latter gives 1 December1792［儒略曆20 November］).
^This is a quote from G. B. Halsted's translator's preface to his 1914 translation of The Theory of Parallels: "What Vesalius was to Galen, what Copernicus was to Ptolemy that was Lobachevsky to Euclid." — W. K. Clifford
