• The Rise and Fall of the Third International
  Written by Ted Grant in 1943.

• The Rise of Stalinism
  Part Two of Ted Grant's book Russia: from Revolution to Counterrevolution

• The Revolution Betrayed - a Marxist masterpiece (by Alan Woods)

For more on this topic, we also recommend the following works by Trotsky:

• The New Course (1923)
• On The Suppressed Testament of Lenin (1926)
• Platform of the Opposition (1927)
• The class nature if the Soviet State (1933)
• The workers' state, Thermidor and Bonapartism (1935)
• The Revolution Betrayed (1936)
• Stalinism and Bolshevism (1937)
• The Stalin School of falsification (1937)