1997 IUCN red list of threatened plants (1997)

Botanischer Jahresbericht - Just, Johann Leopold, 1841 -1891 (Gebr. Borntraeger, 1876)

Phytologia - Moldenke, Harold N. (Harold Norman), 1909 -1996 (H.A. Gleason and H.N. Moldenke, 1970)

Smithsonian contributions to botany - Smithsonian Institution (Smithsonian Institution Press, 2012)

Smithsonian contributions to botany - Smithsonian Institution (Smithsonian Institution Press, 2012)

Smithsonian contributions to botany - Smithsonian Institution (Smithsonian Institution Press, 2012)

The World List of Threatened Trees (1998)