APA (7th ed.) Citation

Bolton, W. F. (1986). The Middle Ages (Rev. & republished.). Sphere Reference.

Chicago Style (17th ed.) Citation

Bolton, W. F. The Middle Ages. Rev. & republished. London: Sphere Reference, 1986.

MLA (9th ed.) Citation

Bolton, W. F. The Middle Ages. Rev. & republished. Sphere Reference, 1986.