APA (7th ed.) Citation

Christopher Helm & Harrison, P. (1996). Seabirds of the world: A photographic guide. Christopher Helm.

Chicago Style (17th ed.) Citation

Christopher Helm and P. Harrison. Seabirds of the World: A Photographic Guide. London: Christopher Helm, 1996.

MLA (8th ed.) Citation

Christopher Helm and P. Harrison. Seabirds of the World: A Photographic Guide. Christopher Helm, 1996.