APA (7th ed.) Citation

Keller, C. D., & Downs, R. B. (1981). American library resources cumulative index, 1870-1970. American Library Association.

Chicago Style (17th ed.) Citation

Keller, Clara D., and Robert B. Downs. American Library Resources Cumulative Index, 1870-1970. Chicago: American Library Association, 1981.

MLA (9th ed.) Citation

Keller, Clara D., and Robert B. Downs. American Library Resources Cumulative Index, 1870-1970. American Library Association, 1981.