APA (7th ed.) Citation

Tolkien, J. R. R., & Tolkien, B. (1999). Letters from Father Christmas (Rev. ed.). HarperCollins.

Chicago Style (17th ed.) Citation

Tolkien, J. R. R., and Baillie Tolkien. Letters from Father Christmas. Rev. ed. London: HarperCollins, 1999.

MLA (8th ed.) Citation

Tolkien, J. R. R., and Baillie Tolkien. Letters from Father Christmas. Rev. ed. HarperCollins, 1999.