pseudonym vs surname

pseudonym

noun
  • A fictitious name (more literally, a false name), as those used by writers and movie stars. 

surname

noun
  • The name a person shares with other members of that person's family, distinguished from that person's given name or names; a family name. 

  • The cognomen of Roman names. 

verb
  • To call by a surname. 

  • To give a surname to. 

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