"Showy Lady's-slipper Cypripedium reginae"(PDF). Natural Heritage & Endangered Species Program. Massachusetts Division of Fisheries & Wildlife. Archived from the original(PDF) on May 27, 2016. Retrieved June 19, 2016.
natureserve.org
NatureServe (2006), "Cypripedium reginae", NatureServe Explorer: An online encyclopedia of life, Version 6.1., Arlington, Virginia, archived from the original on September 29, 2007, retrieved June 13, 2007{{citation}}: CS1 maint: location missing publisher (link)
NatureServe (2006), "Cypripedium reginae", NatureServe Explorer: An online encyclopedia of life, Version 6.1., Arlington, Virginia, archived from the original on September 29, 2007, retrieved June 13, 2007{{citation}}: CS1 maint: location missing publisher (link)
"Showy Lady's-slipper Cypripedium reginae"(PDF). Natural Heritage & Endangered Species Program. Massachusetts Division of Fisheries & Wildlife. Archived from the original(PDF) on May 27, 2016. Retrieved June 19, 2016.