* Martin Gardner, "Non-Euclidean Geometry", Chapter 14 of "The Colossal Book of Mathematics", W.W.Norton & Company, 2001, ISBN 0-393-02023-1* M. J. Greenberg, "Euclidean and Non-Euclidean Geometries: Development and History", 4th edition, W. H. Freeman, 2008.
==See also==*Saccheri–Legendre theorem*Hyperbolic geometry*Parallel postulate*List of Jesuit scientists*List of Roman Catholic cleric–scientists==References==* Martin Gardner, "Non-Euclidean Geometry", Chapter 14 of "The Colossal Book of Mathematics", W. W.Norton & Company, 2001, ISBN 0-393-02023-1* M. J. Greenberg, "Euclidean and Non-Euclidean Geometries: Development and History", 4th edition, W. H. Freeman, 2008.