References for Non-Euclidean Geometry - A bibliographic reference list of books and articles on non-Euclidean geometries, part of the MacTutor History of Mathematics archive. - http://www-history.mcs.st-andrews.ac.uk/history/HistTopics/References/Non-Euclidean_geometry.html
Non-Euclidean Geometry - Mathematics and the Liberal Arts - A resource for student research projects and for teachers interested in using the history of mathematics in their courses. - http://math.truman.edu/~thammond/history/NonEuclideanGeometry.html
Spherical Trigonometry, Arc Distance Formula - Finding the shortest distance between two points on the earth given latitude and longitude. Download ARC_CALC_3, Microsoft Excel version, A Spherical Triangle Calculator by James Q. Jacobs. - http://www.jqjacobs.net/astro/arc_form.html
Non-Euclidean Geometry with LOGO - Review of a new version of LOGO developed at Cardiff. - http://www.bham.ac.uk/ctimath/reviews/logo.html
Non-Euclidean Geometry - A historical account with links to biographies of some of the people involved. - http://www-groups.dcs.st-andrews.ac.uk/~history/HistTopics/Non-Euclidean_geometry.html