APA (7th ed.) Citation

Boyce, R. F., Chamberlin, D. D., King, I., & Hammer, M. M. (1975). Specifying Queries as Relational Expressions: The SQUARE Data Sublanguage. Communications of the ACM, 18(11), 621. https://doi.org/10.1145/361219.361221

Chicago Style (17th ed.) Citation

Boyce, Raymond F., Donald D. Chamberlin, III King, and Michael M. Hammer. "Specifying Queries as Relational Expressions: The SQUARE Data Sublanguage." Communications of the ACM 18, no. 11 (1975): 621. https://doi.org/10.1145/361219.361221.

MLA (9th ed.) Citation

Boyce, Raymond F., et al. "Specifying Queries as Relational Expressions: The SQUARE Data Sublanguage." Communications of the ACM, vol. 18, no. 11, 1975, p. 621, https://doi.org/10.1145/361219.361221.