This 1899 polemic by the famous "Red Rosa" Luxemburg explains why capitalism can never overcome its internal contradictions. An effective refutation of revisionist interpretations of Marxist doctrine, it defines the position of scientific socialism on the issues of social reforms, the state, democracy, and the character of the proletarian revolution. Unabridged republication of the second edition published by Three Arrows Press, New York, 1937.
Here's a sample of other books in this Dover category
Anarchism and Other Essays by Emma Goldman 12 essays by the influential radical include "Marriage and Love," "The Hypocrisy of Puritanism," "The Traffic in Women," Anarchism," and "The Psychology of Political Violence."
The Essential Marx by Leon Trotsky, Karl Marx Compact and fascinating, this invaluable work not only presents Marx's thoughts in his own words, it places them in the swirling context of the early 20th century.
The Revolution Betrayed by Leon Trotsky, Max Eastman One of Marxism's most important texts, this 1936 polemic explores the fate of the Russian Revolution after Lenin's death. A brilliant and profound evaluation of Stalinism, it prophesies the inevitable collapse of the Soviet Union.