special of the group GL1 imply the Artin reciprocity law. Yamamoto's reciprocity law Yamamoto's reciprocity law is a reciprocity law related to class numbers of quadratic number fields. See also Hilbert's ninth problem Stanley's reciprocity theorem References . Correction, ibid. 80 (1973), 281. Survey articles Reciprocity laws and Galois representations: recent breakthroughs Algebraic number theory