APA (7th ed.) Citation

Richards, E. H., & Weekes, M. G. (1921). Straw filters for sewage purification. Engineering & Contracting., 56, 500.

Chicago Style (17th ed.) Citation

Richards, E. H., and M. G. Weekes. "Straw Filters for Sewage Purification." Engineering & Contracting. 56 (1921): 500.

MLA (9th ed.) Citation

Richards, E. H., and M. G. Weekes. "Straw Filters for Sewage Purification." Engineering & Contracting., vol. 56, 1921, p. 500.