A-bomb vs atomic bomb

A-bomb

noun
  • An atomic bomb; a weapon that derives its energy from nuclear reactions and has enormous destructive power. 

verb
  • To bomb with an atom bomb. 

atomic bomb

noun
  • A nuclear weapon that obtains its destructive energy from nuclear fission. 

  • The possession of one or more atomic bombs; the ability to launch a nuclear attack. 

How often have the words A-bomb and atomic bomb occurred in a corpus of books? (source: Google Ngram Viewer )