Brian J. Teppen HyperChem, release 2: molecular modeling for the personal computer. 757-759 1992 32 Journal of Chemical Information and Computer Sciences 6 http://pubs.acs.org/cgi-bin/archive.cgi/jcisd8/1992/32/i06/f-pdf/f_ci00010a025.pdf db/journals/jcisd/jcisd32.html#Teppen92