"Materialism and Empirio-criticism: Critical Comments on a Reactionary Philosophy (1908)". Book by Vladimir Lenin. Chapter Two: "The Theory of Knowledge of Empirio-Criticism and of Dialectical Materialism". Collected Works, Volume 14, www.marxists.org.
"Meeting Of The All-Russia Central Executive Committee". Book by Vladimir Lenin, Collected Works, Vol. 26, pp. 285-293, www.marxists.org. November 4, 1917.