Manuel Garbalena William C. Herndon Optimum graph-theoretical models for enthalpic properties of alkanes. 37-42 1992 32 Journal of Chemical Information and Computer Sciences 1 http://pubs.acs.org/cgi-bin/archive.cgi/jcisd8/1992/32/i01/f-pdf/f_ci00005a006.pdf db/journals/jcisd/jcisd32.html#GarbalenaH92