codex vs sketchbook

codex

noun
  • An early manuscript book. 

  • An official list of medicines and medicinal ingredients. 

  • A book bound in the modern manner, by joining pages, as opposed to a rolled scroll. 

sketchbook

noun
  • A book of printed sketches. 

  • A book or pad with blank pages for sketching; a sketch pad. 

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