burrow vs comb through

burrow

verb
  • (with into) to investigate thoroughly 

  • (with adverbial of direction) to move underneath or press up against in search of safety or comfort 

  • to dig a tunnel or hole 

noun
  • A tunnel or hole, often as dug by a small creature. 

  • A heap or heaps of rubbish or refuse. 

comb through

verb
  • To examine scrupulously. 

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