APA (7th ed.) Citation

Higgins, L. G., & Riley, N. D. (1993). A field guide to the butterlies of Britain and Europe. Harper Collins Publishers.

Chicago Style (17th ed.) Citation

Higgins, Lionel G., and Norman D. Riley. A Field Guide to the Butterlies of Britain and Europe. London: Harper Collins Publishers, 1993.

MLA (8th ed.) Citation

Higgins, Lionel G., and Norman D. Riley. A Field Guide to the Butterlies of Britain and Europe. Harper Collins Publishers, 1993.

Warning: These citations may not always be 100% accurate.