APA (7th ed.) Citation

Hopkinson, A. S., Foster, J., & Billington, R. J. (1967). Rev. Educational Explorers.

Chicago Style (17th ed.) Citation

Hopkinson, Alfred Stephan, John Foster, and Raymond J. Billington. Rev. Reading (Berks.): Educational Explorers, 1967.

MLA (8th ed.) Citation

Hopkinson, Alfred Stephan, et al. Rev. Educational Explorers, 1967.