Systematics of subgen. Pleurothallis sect. Abortivae, sect. Truncatae, sect. Pleurothallis, subsect. Acroniae, subsect. Pleurothallis, subgen. Dracontia, subgen. Unciferia ; Addenda to Dracula, Lepanthes, Masdevallia, Porroglossum and Scaphosepalum - Luer, Carlyle August 1922-2019 (Missouri Botanical Garden, 1998)