c(person("Jeffrey", "Horner", role = "ctb"),
    person("Yihui", "Xie", role = c("aut", "cre"), email = "xie@yihui.name"))
Guesses the MIME type from a filename extension using the data
    derived from /etc/mime.types in UNIX-type systems.
Jeffrey Horner [ctb],
  Yihui Xie [aut, cre]