@conference{visitor,
  title = "The VISITOR Pattern as a Reusable, Generic, Type-Safe Component",
  author = "Bruno C. d. S. Oliveira, Meng Wang, Jeremy Gibbons",
  year = "2008",
  booktitle = "Proceedings of the Object-Oriented Programming, Systems, Languages, and Applications",
  location = "Nashville, TN, USA",
  month = "October",
}