APA (7th ed.) Citation

Sexton, B. C., Wilgenhof, K., & Gopsill, F. P. (1991). Supplementary Interlingua-English dictionary. British Interlingua Society.

Chicago Style (17th ed.) Citation

Sexton, B. C., K. Wilgenhof, and F. P. Gopsill. Supplementary Interlingua-English Dictionary. Sheffield, England: British Interlingua Society, 1991.

MLA (9th ed.) Citation

Sexton, B. C., et al. Supplementary Interlingua-English Dictionary. British Interlingua Society, 1991.