APA (7th ed.) Citation

Durell, C. V., & Robson, A. (1949). Key to advanced trigonometry (1st ed., Repr.). G. Bell and Sons.

Chicago Style (17th ed.) Citation

Durell, Clement V., and A. Robson. Key to Advanced Trigonometry. 1st ed., Repr. London: G. Bell and Sons, 1949.

MLA (9th ed.) Citation

Durell, Clement V., and A. Robson. Key to Advanced Trigonometry. 1st ed., Repr. G. Bell and Sons, 1949.