@article{MR1415316,
  title = "The extensions of the generalized quadrangle of order {$(3,9)$}",
  author = "Pasechnik, Dmitrii V.",
  year = "1996",
  issn = "0195-6698",
  journal = "European J. Combin.",
  mrnumber = "MR1415316 (98a:51010)",
  number = "8",
  pages = "751--755",
  volume = "17",
}