Cita APA (7a ed.)

Wagner, R. (1899). Briefe an Emil Heckel. [s.n.].

Cita Chicago Style (17a ed.)

Wagner, Richard. Briefe an Emil Heckel. Berlin: [s.n.], 1899.

Cita MLA (9a ed.)

Wagner, Richard. Briefe an Emil Heckel. [s.n.], 1899.