bookend vs bookshelf

bookend

noun
  • A heavy object or moveable support placed at one or both ends of a row of books for the purpose of keeping them upright. 

  • Something that comes before, after, or at both sides of something else. 

verb
  • To come before and after, or at both sides of. 

bookshelf

noun
  • A shelf or shelves for storing books for easy visual reference. 

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