Wesley Alan Wright of the University of Vermont's Computer Services did most of the javascript and HTML for this site (and has been wonderfully patient with all my frequent questions and requests.)

The introductory section's use of Magritte's painting was inspired by a passage that makes a similar point using different vocabulary in Scott McCloud's excellent Understanding Comics. And the practice of using the Web to teach this material was pioneered by Prof. Daniel Chandler's web site, Semiotics for Beginners.