http://eos.kub.nl:2080/w3thesis/Readthis/barfield1993.html (Einblicke ins Internet, 10/1995)Author: 
Barfield, L.
Title: The user interface - Concepts & design
Book: ISBN 0-201-54441-5
Published by: Addison-Wesley Publishing Company Inc., 1993
Remarks: Nowadays, Lon Barfield is working for 
.
Sjoerd Michels, Tilburg, The Netherlands