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This lecture honors the memory of Robert Wartenberg, who was born in Lithuania, trained in Germany, and in 1935 moved to the United States, where he started his second career as a scholar and teacher at the University of California, San Francisco.1 The author thanks Drs. Eric A. Schon and Michio Hirano for collaboration and Pablo Abreu for help with the figures.
Salvatore DiMauro (Mon,) studied this question.