APA (7th ed.) Citation

Hansen, R., Stahl, F., & Ward, R. (1993). Perennials and their garden habitats (4th ed.). Timber Press.

Chicago Style (17th ed.) Citation

Hansen, Richard, Friedrich Stahl, and Richard Ward. Perennials and Their Garden Habitats. 4th ed. Portland, Or.: Timber Press, 1993.

MLA (9th ed.) Citation

Hansen, Richard, et al. Perennials and Their Garden Habitats. 4th ed. Timber Press, 1993.