The author of Mathpages com I discovered I have made a mistake I was in error in stating that the author of the online boek reflections on relativity is Jonathan Vos Post I discovered that the site Mathpages com is maintained by someone called Kevin Brown I have not been able to find background information about this Kevin Brown Possibly it is a pseudonym Jonathan Vos Post is a mathematicion and he also has math material online MATH Pages of Jonathan Vos Post It seemed to fit