Cita APA (7th ed.)

Ruhrberg, K., & Gilles, W. (1987). Werner Gilles - Ölbilder, Aquarelle, Graphik: [Text: Karl Ruhrberg].

Cita Chicago (17th ed.)

Ruhrberg, Karl, i Werner Gilles. Werner Gilles - Ölbilder, Aquarelle, Graphik: [Text: Karl Ruhrberg]. Düsseldorf, 1987.

Cita MLA (8th ed.)

Ruhrberg, Karl, i Werner Gilles. Werner Gilles - Ölbilder, Aquarelle, Graphik: [Text: Karl Ruhrberg]. 1987.