APA (7th ed.) Citation

Howe, J., Tolkien, C., Tolkien, J. R. R., & Sibley, B. (1999). The map of Tolkien's Beleriand and the lands to the north. HarperCollins.

Chicago Style (17th ed.) Citation

Howe, John, Christopher Tolkien, J. R. R. Tolkien, and Brian Sibley. The Map of Tolkien's Beleriand and the Lands to the North. London: HarperCollins, 1999.

MLA (8th ed.) Citation

Howe, John, et al. The Map of Tolkien's Beleriand and the Lands to the North. HarperCollins, 1999.