Non-Euclidean geometry that are both perpendicular to a third line: Euclidean geometry, named after the Greek mathematician Euclid, includes some of the oldest known mathematics, and geometries that deviated from this were not widely accepted as legitimate until the 19th century. The debate that eventually led to the discovery of the non-Euclidean geometries began almost as soon as Euclid's work "Elements" was written. In the "Elements", Euclid began with a limited number of assumptions (23 definitions, five common notions, and five postulates) and sought to prove all the other results (propositions) in the work. The most notorious of the postulates is often
The Oxford Textbook of Medicine Research in Health programme. The "Oxford Textbook of Medicine" is edited by: In total, there are 750 contributors to the textbook. The Oxford Textbook of Medicine The Oxford Textbook of Medicine is an international textbook of medicine. First published in 1983, it is now in its fifth edition. It is primarily aimed at mature physicians looking for information outside their area of particular expertise, but widely used as a reference source by medical students and doctors in training, and by others seeking authoritative accounts of the science and clinical practice of medicine. The "Oxford Textbook of Medicine" is available in