APA (7th ed.) Citation

Retief, E., & Herman, P. P. (1997). Plants of the northern provinces of South Africa: Keys and diagnostic characters. National Botanical Inst.

Chicago Style (17th ed.) Citation

Retief, E., and Paul P. Herman. Plants of the Northern Provinces of South Africa: Keys and Diagnostic Characters. Pretoria: National Botanical Inst, 1997.

MLA (9th ed.) Citation

Retief, E., and Paul P. Herman. Plants of the Northern Provinces of South Africa: Keys and Diagnostic Characters. National Botanical Inst, 1997.