memorabilia vs memorandum

memorabilia

noun
  • Things worth remembering: noteworthy points. 

  • Objects that are connected to or remind their owner of past events. 

memorandum

noun
  • A short note serving as a reminder. 

  • A brief diplomatic communication. 

  • A written business communication. 

  • A page in an annual publication honoring the memory of a person who died during the past year. 

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