APA

Pettifer Julian, Brown Robin & Whitehead Malcolm. (1994). Nature watch. London: HarperCollins.

Chicago

Pettifer Julian, Brown Robin and Whitehead Malcolm. 1994. Nature watch. London: HarperCollins.

Harvard

Pettifer Julian, Brown Robin and Whitehead Malcolm. (1994). Nature watch. London: HarperCollins.

MLA

Pettifer Julian, Brown Robin and Whitehead Malcolm. Nature watch. London: HarperCollins. 1994.