Your friend is mistaken. When I created Babylon 5 -- my own concept
-- Warners did a search to make sure that the title hadn't been used or
copyrighted elsewhere. The search turned up a number of Babylon 2's, one
Babylon 3, and an unpublished song entitled Babylon 4, but happily, no
Babylon 5. There has not been a book published with that name, insofar
as we have ever been able to tell. It's most likely that what your friend
is thinking of is a book entitled "Alas, Babylon," by Pat Frank, which is
a very fine novel indeed, and was written in about the period you mention.

jms