F. De Laet A Linear Line Notation for Flow Patterns in the Chemical Industry. 50-55 1977 17 Journal of Chemical Information and Computer Sciences 1 http://pubs.acs.org/cgi-bin/archive.cgi/jcisd8/1977/17/i01/f-pdf/f_ci60009a013.pdf db/journals/jcisd/jcisd17.html#Laet77