Edlyn S. Simmons Central Patents Index Chemical Code: a user's viewpoint. 10-15 1984 24 Journal of Chemical Information and Computer Sciences 1 http://pubs.acs.org/cgi-bin/archive.cgi/jcisd8/1984/24/i01/f-pdf/f_ci00041a004.pdf db/journals/jcisd/jcisd24.html#Simmons84