1997 IUCN red list of threatened plants (1997)

Checklist of CITES Species (1998)

Checklist of CITES Species and Annotated CITES Appendices and Reservations - Inskipp, Tim (CITES Secretariat, UNEP-WCMC, 2005)

Checklist of CITES Species: a reference to the appendices to the Convention on International Trade in Endangered Species of Wild Fauna and Flora (2003)

Checklist of CITES Species: a reference to the appendices to the Convention on International Trade in Endangered Species of Wild Fauna and Flora (1996)

Checklist of CITES Species: a reference to the appendices to the Convention on International Trade in Endangered Species of Wild Fauna and Flora (2001)

Flora of tropical Africa - Oliver, Daniel, 1830 -1916 (L. Reeve and co, 1909)

Just's Botanischer Jahresbericht - Just, Johann Leopold, 1841 -1891 (Gebruder Borntraeger, 1913)

Monograph of the voles and lemmings (Microtinae) living and extinct - Hinton, Martin A. C. (Martin Alister Campbell), 1883 -1961 (1826)