@Unpublished{     gessel-slides,
  Author        = "Gessel, Ira",
  date-added    = "2023-03-11 23:02:42 +0100",
  date-modified = "2023-03-11 23:02:58 +0100",
  Title         = "An Introduction to Combinatorial Species",
  File          = "An Introduction to Combinatorial Species - species-intro - a.pdf"
}

@Unpublished{ gessel-slides, Author = "Gessel, Ira", date-added = "2023-03-11 23:02:42 +0100", date-modified = "2023-03-11 23:02:58 +0100", Title = "An Introduction to Combinatorial Species", File = "An Introduction to Combinatorial Species - species-intro - a.pdf" }