Cita APA

Hertel, R. F., Maass, T., & Muller, V. R. (1991). Nickel. Geneva: World Health Organization.

Citación estilo Chicago

Hertel, R. F., T. Maass, y V. R. Muller. Nickel. Geneva: World Health Organization, 1991.

Cita MLA

Hertel, R. F., T. Maass, y V. R. Muller. Nickel. Geneva: World Health Organization, 1991.