Abstract
I am greatly indebted to the Institute for Scientific Information for two volumes of the IDR&DS not available at the Ruhr-University, to Derek J. de Solla Price of Yale University for a critical review of this paper, to Helmut Baitsch of University of Ulm for many valuable suggestions, to Helga Niehr, Werner Ruzicka, Lothar Schneidt and Ulrich König for helping me in the counting and computing, and to Günter Keim for drawing the figures.