Implementation of two hidden-line algorithms. - Michael Potmesil; H. Freeman (Comput. Graph., 1980)

The Open Channel. - H. Freeman; William E. Drissel (Computer, 1987)

Use of the surface-attribute probe for 3-D object characterization. - Y. Tan; H. Freeman (ICPR (1), 1994)

From concept to delivery: a new tool for courseware developers. - H. Freeman; S. Ryan (WCCE, 1995)