@book{riggs1893,
  address   = {Washington},
  author    = {Riggs, R. S.},
  key       = {Riggs (1893)},
  pages     = {1-232},
  publisher = {U.S. Government Printing Office},
  series    = {U. S. Geol. Surv., Contr. N. Amer. Ethn.},
  title     = {Dakota Grammar, Texts, and Ethnography},
  volume    = {9},
  year      = {1893}
}