completion vs preface

completion

noun
  • The act or state of being or making something complete; conclusion, accomplishment. 

  • The space resulting from such an act. 

  • The conclusion of an act of conveyancing concerning the sale of a property. 

  • The act of making a metric space complete by adding points. 

  • A forward pass that is successfully caught by the intended receiver. 

preface

noun
  • An introduction, or series of preliminary remarks. 

  • A title or epithet. 

  • The beginning or introductory portion that comes before the main text of a document or book. 

  • The prelude or introduction to the canon of the Mass. 

verb
  • To give a preface to. 

  • To introduce or make a comment before (the main point). 

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