== 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.  
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