1997 IUCN red list of threatened plants (1997)

Monographs in systematic botany from the Missouri Botanical Garden - Missouri Botanical Garden. (Missouri Botanical Garden, 2000)

Monographs in systematic botany from the Missouri Botanical Garden - Missouri Botanical Garden. (Missouri Botanical Garden, 2000)

Orchids of Panama : a facsimile reprint of the Orchidaceae, Flora of Panama - Williams, Louis O. 1908 -1991 (Missouri Botanical Garden, 1980)