APA (7th ed.) Citation

Gaarder, J., Rokkan, E., & Gibb, S. (1992). The christmas mystery. Dolphin Paperback.

Chicago Style (17th ed.) Citation

Gaarder, Jostein, Elizabeth Rokkan, and Sarah Gibb. The Christmas Mystery. London: Dolphin Paperback, 1992.

MLA (9th ed.) Citation

Gaarder, Jostein, et al. The Christmas Mystery. Dolphin Paperback, 1992.