This report discusses the use of the Science Citation Index produced by the Institute for Scientific Information (ISI) as a given "expert system" in the experimental study of different search levels. The inquiry has two objectives: (1) to test whether a "traditional" information system will also produce the rudiments of a knowledge-based system; and (2) to provide a guide to the Science Citation Index for German users. It is noted that the results obtained are of preliminary character and that further studies should improve the method and the time span searched. Some general remarks about "objective knowledge,""subjective knowledge," and "information" are also included. The text is supplemented with 22 figures, and a 19-item bibliography is provided. (Author/EW)