APA (7th ed.) Citation

Tolkien, J. R. R., & Tolkien, C. (1990). Unfinished tales of Númenor and Middle-earth. Harper Collins.

Chicago Style (17th ed.) Citation

Tolkien, J. R. R., and Christopher Tolkien. Unfinished Tales of Númenor and Middle-earth. London: Harper Collins, 1990.

MLA (8th ed.) Citation

Tolkien, J. R. R., and Christopher Tolkien. Unfinished Tales of Númenor and Middle-earth. Harper Collins, 1990.