Atwood, John T., and Norris H. Williams. “THE UTILITY OF EPIDERMAL CELL FEATURES IN PHRAGMIPEDIUM AND PAPHIOPEDILUM (ORCHIDACEAE) FOR DETERMINING STERILE SPECIMENS”. Selbyana 2, no. 4 (December 1, 1978): 356–366. Accessed December 18, 2024. https://journals.flvc.org/selbyana/article/view/120427.