1997 IUCN red list of threatened plants (1997)

Index Kewensis plantarum phanerogamarum. nomina et synonyma omnium generum et specierum ab initio anni MDCCCCLXI usque ad finem anni MDCCCCLXV nonnulla etiam antea edita complectens Supplementum quartum decimum - Royal Botanic Gardens, Kew. (e prelo Clarendoniano)

International review of the science and practice of agriculture - International Institute of Agriculture. Bureau of Agricultural Intelligence; Plant Diseases. (International Institute of Agriculture, Bureau of Agricultural Intelligence and Plant Diseases, 1916)

South African journal of natural history - South African Biological Society. (South African Biological Society, 1921)

The World List of Threatened Trees (1998)