Karl Erich Wolff Wendsomde Yameogo Time Dimension, Objects, and Life Tracks. A Conceptual Analysis. 188-200 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2746&spage=188 2003 conf/iccs/2003 ICCS db/conf/iccs/iccs2003.html#WolffY03