APA (7th ed.) Citation

Clapham, A. R., Tutin, T. G., & Warburg, E. F. (1959). Excursion flora of the British Isles. Univ. Pr.

Chicago Style (17th ed.) Citation

Clapham, A. R., Thomas Gaskell Tutin, and E. F. Warburg. Excursion Flora of the British Isles. Cambridge: Univ. Pr, 1959.

MLA (9th ed.) Citation

Clapham, A. R., et al. Excursion Flora of the British Isles. Univ. Pr, 1959.