Rabinowitz, Deborah (1981). "Seven forms of rarity"(PDF). Biological Aspects of Rare Plant Conservation. Archived from the original(PDF) on 2017-12-15. Retrieved 2019-03-26.
Rabinowitz, Deborah (1981). "Seven forms of rarity"(PDF). Biological Aspects of Rare Plant Conservation. Archived from the original(PDF) on 2017-12-15. Retrieved 2019-03-26.