John Howse The Iconic Logic of Peirce's Graphs: Sun-Joo Shin MIT Press, Cambridge, MA, 2002 ISBN: 0-262-19470-8. 119-121 2003 14 J. Vis. Lang. Comput. 1 http://dx.doi.org/10.1016/S1045-926X(02)00075-7 db/journals/vlc/vlc14.html#Howse03