At that time there were parallel lectures in German and French. Kollros attended only the French lectures, as he mentions in his reminiscences published (in connection with a celebration held in Bern) for the 50th anniversary in 1955 of the theory of special relativity. Louis Kollros: Albert Einstein en Suisse: Souvenirs. In: Helvetica Physica Acta. Supplementum 4, 1956, pp. 271-281, and as a German translation: Erinnerungen eines Kommilitonen. In: Carl Seelig (ed.): Helle Zeit – dunkle Zeit: In memoriam Albert Einstein. Europa Verlag, Zürich 1956, pp. 17–31 doi:10.1007/978-3-322-84225-1_3
