APA (7th ed.) Citation

Rankin, R. A. (1969). The modular group and its subgroups.

Chicago Style (17th ed.) Citation

Rankin, Robert A. The Modular Group and Its Subgroups. Madras, 1969.

MLA (9th ed.) Citation

Rankin, Robert A. The Modular Group and Its Subgroups. 1969.

Warning: These citations may not always be 100% accurate.