APA

Ferm V. T. A., . (1950). A history of philosophical systems. New York: Philosophical Library.

Chicago

Ferm Vergilius Ture Anselm, . 1950. A history of philosophical systems. New York: Philosophical Library.

Harvard

Ferm V. T. A., . (1950). A history of philosophical systems. New York: Philosophical Library.

MLA

Ferm Vergilius Ture Anselm, . A history of philosophical systems. New York: Philosophical Library. 1950.