by Roberto Bonola ; authorized English translation with additional appendices by H.S. Carslaw ; with an introduction by Federigo Enriques ; with a supplement containing the Dr. George Bruce Halsted translations of The science of absolute space by John Bolyai ; The theory of parallels by Nicholas LobachevskiDover1955
by Roberto Bonola ; authorized English translation with additional appendices by H.S. Carslaw ; with an introduction by Federigo EnriquesThe Open Court Pub. Co.1938, c1912