plectrum vs quill pen

plectrum

noun
  • A small piece of plastic, metal, ivory, etc., for plucking the strings of a guitar, lyre, mandolin, etc. 

  • A projection of bone or other stiff tissue, such as the ridges in some insects' stridulatory organs. 

quill pen

noun
  • A pen (writing instrument) made from a quill (a wing or tail feather of a large bird). 

How often have the words plectrum and quill pen occurred in a corpus of books? (source: Google Ngram Viewer )