1. Mileva Manc; also sometimes spelled “Maritsch” and “Marity”. For the German version of this letter see Albert Einstein, Vol. I edited by John Stachel, Princeton University Press: Princeton, 1987, pp. 260–261.
2. Einstein was presumably refemng to Boltzmann’s Vorlesungen über Gastheorie, Barth: Leipzig, either Volume I published in 1896 or Volume II published in 1898. For Einstein’s early work on statistical mechanics see Clayton A. Gearhart, “Einstein Before 1905: The Early Papers on Statistical Mechanics”, American Journal of Physics,58(1990)468–480.
3. Franz S. Exner (1849–1926) became Professor of experimental physics at the University of Vienna in 1891, succeeding Joseph Loschmidt. His father had been an influential philosopher and educator and several close relatives were also scientists. Exner did much work in electrochemistry and in the study of atmosphenc phenomena. He also was a very influential teacher, guiding more students to higher degrees in Vienna than either of his better-known contemporaries, Boltzmann or Mach. See B. Karlik and E. Schmid, Franz Exner und sein Kreis, österreichische Akademie der Wissenschaften Verlag: Vienna, 1982.
4. Leopold Gegenbauer (1849–1903) became Professor of Mathematics at the University of Vienna in 1893.
5. Mileva Maric (1875–1948) seems to have grown up in a Serbian family living in the town of Titel in what was then southern Hungary. She became a fellow student of Einstein in the ETH in Zürich. They had three children, one before and two after marriage. See The Collected Papers of Albert Einstein, Vol. I edited by John Stachel, Princeton University Press: Princeton, 1987, pp. 272–273 and 380–381 and Albert Einstein Mileva Maric - The Love Letters, edited by J. Renn and R. Schulmann and translated by Shawn Smith, Princeton University Press: Princeton, 1992.