Blinova, Ilona. “A Northernmost Population of Cypripedium Calceolos L. (Orchidaceae): Demography, Flowering, and Pollination”. Selbyana 23, no. 1 (February 1, 2002): 111–120. Accessed August 10, 2024. https://journals.flvc.org/selbyana/article/view/121631.