hajduk vs snake in the grass

hajduk

noun
  • An outlaw, highwayman, or freedom fighter in the Balkans. 

  • A halberdier of a Hungarian noble. 

  • An attendant in German or Hungarian courts. 

snake in the grass

noun
  • A hidden enemy. 

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