documentalist vs documentarian

documentalist

noun
  • A person, especially a librarian, who is an expert in documents and documentation. 

documentarian

noun
  • A person who cares about communication and documentation. 

  • Somebody who advocates the documentary hypothesis. 

  • A person whose profession is to create documentary films. 

  • A person who writes software documentation. 

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