Photo by Scherer, Nabholz, and К°, 1887 10.9 х 16.4 cm Back side autographed: “To my former student Olga Nikolaevna Dobroliubova for good memories from P. Pokrovskii” Petr Mikhailovich POKROVSKII (1857 - 1901), Ph.D., graduated from Moscow University and continued to teach there for a while. Commissioned overseas, Pokrovskii studied in Berlin, Germany. In 1881, he began teaching at theoretical mathematics at St. Vladimir’s University in Kiyv, Russian Empire (today Ukraine). Pokrovsky was member of several math societies, including Moscow, Kyiv, Kazan, and several foreign societies. POKROVSKII, P. M. (Покровкий П.М.)