mathematical notes commentaries blanchard coll sciences dans l'histoire paris external links roberto bonola https archiveorg details noneuclideangeom bonorich non euclidean geometry open court chicago http www groupsdcsst andacuk history histtopics non euclidean geometryhtml mactutor archive article non euclidean geometry http wwwencyclopediaofmathorg indexphp non euclidean geometries non euclidean geometries ''encyclopedia math'' european mathematical society springer science business media https wwwwebcitationorg koaax cturl http cageocitiescom cocklebio synsptmhtml synthetic spacetime digest axioms used theorems proved wilson lewis archived webcite
Formal science Mathematics Pure mathematics Geometry Non-Euclidean geometry