Carslaw, H.S. . The Elements of Non Euclidean Geometry and Trigonometry / Textual Documents H.S.Carslaw. - 1st ed. / - New York : Longmans Green & Co , 1916. - 175p. : ill ; 19cm . Index Subjects--Index Terms: Geometry-Non Euclidean Trigonometry-Non Euclidean G-Mathematics Dewey Class. No.: 513.8 / C 238 El