primer vs travel book

primer

noun
  • A children's book intended to teach literacy: how to read, write, and spell. 

  • A layer of such a substance. 

  • A prayer or devotional book intended for laity, initially an abridgment of the breviary and manual including the hours of the Virgin Mary, 15 gradual and 7 penitential psalms, the litany, the placebo and dirige forming the office of the dead, and the commendations. 

  • An introductory text on any subject, particularly basic concepts. 

  • Any of various similar works issued in England for private prayer in accordance with the Book of Common Prayer. 

  • An elementary school class; an elementary school student. (No longer used.) 

  • A molecule which initiates the synthesis of an enzyme, (especially) a single-stranded nucleic acid molecule which initiates DNA replication. 

  • A pheromone which interacts first with the endocrine system. 

  • Any substance or device, such as priming wire or blasting cap, used to ignite gunpowder or other explosive. 

  • A layer of makeup that goes beneath the foundation; undermakeup. 

  • A substance used to prime wood, metal, etc. in preparation for painting. 

  • A device used to prime an internal combustion engine with gasoline, (especially) in airplanes. 

  • A person who prunes trees. 

travel book

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

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