@MISC{OPPCAT_1.MIZ,
  AUTHOR = {Byli\'nski, Czes{\l}aw},
  TITLE = {Opposite Categories and Contravariant Functors},
  DAY = {13},
  MONTH = {February},
  YEAR = {1991},
  ADDRESS1 = {Warsaw University\\Bia{\l}ystok},
  SUMMARY = { The opposite category of a category, contravariant functors and
   duality functors are defined.}}

