^Christopherson, E. 1968: Flowering plants from Tristan da Cunha. Results of the Norwegian scientific Expedition to Tristan da Cunha 1937-1938 55: 1-29.
^Groves, E.W. 1981: Vascular plant collections from the Tristan da Cunha group of islands. Bulletin of the British Museum (Natural History), Botany series 8(4): 333-420.
^Roux, J. P., Ryan, P. G., Milton, S. J. and Moloney C. L. 1992: Vegetation and checklist of Inaccessible Island, central South Atlantic Ocean, with notes on Nightingale Island. Bothalia 22 (1): 93-109.
^Hemsley, William Botting 1884. Report on the Scientific Results of the Voyage of H.M.S. Challenger during the years 1873-76: under the command of Captain George S. Nares and the late Captain Frank Tourle Thomson vol 1, part 2, page 152