novella vs paperback

novella

noun
  • Synonym of novel (“new legal constitution in Ancient Rome”) 

  • A short novel or long short story. 

paperback

noun
  • A book with flexible binding. 

adj
  • Having flexible binding. 

verb
  • To issue or publish (a book) in a paperback edition. 

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