Warning - the bibtex entry below may be invalid: 
Missing 'school' field
@phdthesis{oliveira07genericity,
  author = "Bruno C. d. S. Oliveira",
  title = "Genericity, extensibility and type-safety in the Visitor pattern",
  url = "http://www.comlab.ox.ac.uk/people/Bruno.Oliveira/Thesis.pdf",
  year = "2007",
}