1997 IUCN red list of threatened plants (1997)

Botanisches Zentralblatt; referierendes Organ für das Gesamtgebiet der Botanik - Association internationale des botanistes. (G. Fischer [etc.], 1907)

Bulletin of miscellaneous information - Royal Botanic Gardens, Kew. (H.M. Stationery Office, 1907)

Bulletin of miscellaneous information - Royal Botanic Gardens, Kew. (H.M. Stationery Office, 1907)

Yearbook of the Heather Society - Heather Society (The Society, 1996)