Older sources in Russian—e.g., A. F. Popov, "Воспоминания о службе и трудах проф. Казанского университета Н. И. Лобачевского" ("Memoirs of the Service and Work of N. I. Lobachevsky"), 1857—give 1793 rather than 1972, while the Dictionary of Scientific Biography (1970) gives December 2, 1792. Further information on Lobachevsky's birthdate can be found in: Athanase Papadopoulos (ed.), Nikolai I. Lobachevsky. Pangeometry, European Mathematical Society. 2010, pp. 206–7.
