Parnell, J., Cullen, E. L., Curtis, T., & Webb, D. A. (2011). Webb's an Irish flora ([Eighth edition].). Cork University Press.

Parnell, John, Elaine L. Cullen, Tom Curtis, and D. A. Webb. Webb's an Irish Flora. [Eighth edition]. Cork: Cork University Press, 2011.

Parnell, John, et al. Webb's an Irish Flora. [Eighth edition]. Cork University Press, 2011.