root about vs sift through

root about

verb
  • To search for something in a similar manner. 

  • To rummage; to look for something in a somewhat aimless fashion. 

  • To forage by poking the snout here and there. 

sift through

verb
  • To carefully go through a set of objects, or a collection of information, in order to find something. 

How often have the words root about and sift through occurred in a corpus of books? (source: Google Ngram Viewer )