be a source of strength to vs buck up

be a source of strength to

buck up

intj
  • Cheer up; take courage; take heart. 

verb
  • To pass on to higher authority for resolution. See also pass the buck. 

  • To encourage; to hearten. 

  • To become encouraged, reinvigorated, or cheerful; to summon one's courage or spirits; to pluck up courage. 

How often have the words be a source of strength to and buck up occurred in a corpus of books? (source: Google Ngram Viewer )