allusion vs autosuggestion

allusion

noun
  • An indirect reference; a hint; a reference to something supposed to be known, but not explicitly mentioned 

autosuggestion

noun
  • An instance of suggesting a thought to oneself. 

  • An autosuggest feature. 

  • The practice of suggesting thoughts to oneself, as in autohypnosis. 

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