I'm looking for a primary reference of the altitude classifications of geocentric orbits (LEO, MEO, GEO, HEO), but I was not able to find something so far.
I noticed that there is very different information about this classification scheme, for example LEO: The English Wikipedia defines LEO from 160 to 2.000 km above mean sea level; in comparison, the German Wikipedia defines LEO from 200 to 1.200 km.
Does anybody know if there is an established standard for this orbit classification, e.g. at NASA, ESA or any other space agency, which can be referenced (f.i. a paper, guideline or handbook)?
Thank you really much!