y & Co.Object verification system and methodUS4926031 *Apr 27, 1987May 15, 1990Gao Gesellschaft Fur Automation Und Organisation MbhToken such as credit or identification card and an apparatus for testing the token or cardUS4929821 *Mar 12, 1987May 29, 1990Skidata Computer G.m.b.H.Method of forgery-protecting a data carrier, a forgery-protected data carrier and apparatuses for handling, processing