arrivederci vs don't forget to write

arrivederci

intj

  • farewell, goodbye, see you later (non-definitive farewell) 

noun

  • An Italian farewell by saying "arrivederci". 

don't forget to write

intj

  • Addressed to someone whose departure is permanent or for a long time 

How often have the words arrivederci and don't forget to write occurred in a corpus of books? (source: Google Ngram Viewer )