H
H. S. M. Coxeter
Harold Scott MacDonald "Donald" Coxeter, CC, FRS, FRSC was a British and later also Canadian geometer. He is regarded as one of the greatest geometers of the 20th century. --Wikipedia
Mathematical Expositions, No.2 (Non-Euclidean Geometry)
This book, part of the Mathematical Expositions series, offers a deep exploration into the principles and concepts of Non-Euclidean Geometry. It presents a rigorous academic treatment of the subject, suitable for advanced students and researchers in mathematics. The text covers various aspects of geometries that deviate from Euclidean postulates.