Programming in Three Dimensions
   By Marc Najork. This thesis describes Cube, the first visual language to employ a three-dimensional syntax.
   http://citeseer.ist.psu.edu/najork94programming.html

Visual Programming Language Bibliography
   From POSTECH Software Engineering Lab.
   http://selab.postech.ac.kr/link/vpl.html

Watch What I Do: Programming by Demonstration
   Online book. Reviews.
   http://www.acypher.com/wwid/