1   Ritchie and Thompson; "The Unix Time-Sharing System,"
    Bell System Technical Journal, 57:6.2, July-August 1978.

2   Joy, Bill;  "An Introduction to Display Editing with Vi,"
    University of California at Berkeley Computer Center, 1978.

3   Sherwood, Bruce;  The Tutor Language,  University of Illinois
    at Urbana-Champaign--Computer-Based Education Research
    Laboratory, 1974.

4   Titelman, Warren;  A Visual Lisp Programming System,
    Talk given at The University of California at Berkeley, 1979.