Maoism vs leftism

Maoism

noun
  • The philosophy espoused by Chinese leader Mao Zedong, a form of Marxism-Leninism that focuses on the peasantry as the revolutionary vanguard. 

leftism

noun
  • Belief in the principles of left-wing politics. 

How often have the words Maoism and leftism occurred in a corpus of books? (source: Google Ngram Viewer )