flipcard vs memory stick

flipcard

noun
  • Synonym of flashcard (“card to aid memorization, with a cue on one side and a response on the other”) 

memory stick

noun
  • A portable solid-state electronic flash memory data storage device equipped with a USB (or similarly specified) plug for direct connection to a corresponding port; a USB drive, thumb drive or pen drive. 

  • One of a series of memory devices manufactured by the Sony Corporation ranging in size from a USB drive down to a flash card. 

How often have the words flipcard and memory stick occurred in a corpus of books? (source: Google Ngram Viewer )