Cita APA (7a ed.)

Gregorovius, F. (1879). Urban VIII. . [s.n.].

Cita Chicago Style (17a ed.)

Gregorovius, Ferdinand. Urban VIII. . Stuttgart: [s.n.], 1879.

Cita MLA (9a ed.)

Gregorovius, Ferdinand. Urban VIII. . [s.n.], 1879.