Letnikov, Aleksei Vasil’evich
Born Jan. 1 (13), 1837, in Moscow; died there Feb. 27 (Mar. 10), 1888. Russian mathematician. Corresponding member of the St. Petersburg Academy of Sciences (1884).
Letnikov was appointed a professor at the Moscow Technical School in 1868. He developed the theory of derivatives of arbitrary (fractional and negative) order.