Non-Euclidean Geometry : Fifth Edition
This textbook introduces non-Euclidean geometry, and the third edition adds a new chapter, including a description of the two families of 'mid-lines' between two given lines and an elementary derivation of the basic formulae of spherical trigonometry and hyperbolic trigonometry, and other new material
eBook, English, 1965
University of Toronto Press, Toronto, 1965