Literature

• Boldingh, I. 1909. The flora of the Dutch West Indian Islands St. Eustatius, Saba and St. Martin. 321 pp. E.j. Brill., Leiden.
• Howard, R.A. 1989. Dicotyledoneae - Part 2. In: Flora of the Lesser Antilles, Leeward and Windward Islands. 5: 604. Arnold Arboretum, Harvard University, Jamaica Plain, Massachusetts.
• Mori, S.A., Gracie, C.A. 2007. Flowering Plants. Plants and Lichens of Saba Virtual Herbarium of The New York Botanical Garden. [link]
• The Plant List 2013. The Plant List version 1.1. [link]

Literature references linked to higher taxa

• Encyclopedia of Life. [link] (Cactaceae)