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In page Max Planck:

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Planck started a six-semester course of lectures on theoretical physics, "dry, somewhat impersonal"[citation needed] according to Lise Meitner, "using no notes, never making mistakes, never faltering; the best lecturer I ever heard"[citation needed] according to an English participant, James R. Partington, who continues: "There were always many standing around the room. As the lecture-room was well heated and rather close, some of the listeners would from time to time drop to the floor, but this did not disturb the lecture."[citation needed] Planck did not establish an actual "school"; the number of his graduate students was only about 20, among them:[citation needed]