APA-viite (7. p.)
Urban, W. M. (1897). A History of the principle of sufficient reason: Its metaphysical and logical formulations.
Chicago-viite (17. p.)
Urban, Wilbur Marshall. A History of the Principle of Sufficient Reason: Its Metaphysical and Logical Formulations. Leipzig, 1897.
MLA-viite (9. p.)
Urban, Wilbur Marshall. A History of the Principle of Sufficient Reason: Its Metaphysical and Logical Formulations. 1897.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.