APA (7th ed.) Citation

Rittmann, A., & Rittmann, L. (1976). Volcanoes. Orbis.

Chicago Style (17th ed.) Citation

Rittmann, A., and L. Rittmann. Volcanoes. Londres: Orbis, 1976.

MLA (9th ed.) Citation

Rittmann, A., and L. Rittmann. Volcanoes. Orbis, 1976.