textbook vs travel book

textbook

noun
  • A coursebook, a formal manual of instruction in a specific subject, especially one for use in schools or colleges. 

adj
  • Having the typical characteristics of some class of phenomenon, so that it might be included as an example in a textbook. 

  • Of or pertaining to textbooks or their style, especially in being dry and pedagogical; textbooky, textbooklike. 

travel book

noun
  • A book about travelling to a certain region, such as a memoir or guide book. 

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