MS dedication to Boris Godunov, January 21, 1874. http://www.bklynnews.com/BklynRadio/boris%20godunov-1.htm
Modest Mussorgsky: Frases em inglês
Letter to Lyudmila Shestakova, July 30, 1868; Jay Leyda and Sergei Bertensson The Musorgsky Reader (1947) p. 113.
Letter to Vladimir Stassov, October 18, 1872; Oskar von Riesemann (trans. Paul England) Moussorgsky (1929) p. 107.