APA (7th ed.) Citation

Mullan, B., Norman, P., Boer, H., & Seydel, E. (2015). Protection motivation theory. Open University Press.

Chicago Style (17th ed.) Citation

Mullan, Barbara, P. Norman, H. Boer, and E. Seydel. Protection Motivation Theory. Open University Press, 2015.

MLA (9th ed.) Citation

Mullan, Barbara, et al. Protection Motivation Theory. Open University Press, 2015.