APA (7th ed.) Citation

Howe, J., Tolkien, C., Tolkien, J. R. R., & Sibley, B. (1994). The map of Tolkien's Middle-Earth. HarperCollins.

Chicago Style (17th ed.) Citation

Howe, John, Christopher Tolkien, J. R. R. Tolkien, and Brian Sibley. The Map of Tolkien's Middle-Earth. London: HarperCollins, 1994.

MLA (8th ed.) Citation

Howe, John, et al. The Map of Tolkien's Middle-Earth. HarperCollins, 1994.