MLA

Gierke, Otto von, Ernst Troeltsch, and Ernest Barker. Natural Law and the Theory of Society 1500 to 1800. Cambridge: Cambridge University PRess, 1950.

APA

Gierke, O. von, Troeltsch, E., & Barker, E. (1950). Natural Law and the Theory of Society 1500 to 1800. Cambridge: Cambridge University PRess.

Chicago

Gierke, Otto von, and Ernst Troeltsch. Natural Law and the Theory of Society 1500 to 1800. Translated by Ernest Barker. Cambridge: Cambridge University PRess, 1950.