Cita APA (7th ed.)

Obert, K. B., & Chicurel, S. R. (2005). Geography of the voice.

Cita Chicago (17th ed.)

Obert, Kerrie B., i Steven R. Chicurel. Geography of the Voice. Think Voice International, 2005.

Cita MLA (9th ed.)

Obert, Kerrie B., i Steven R. Chicurel. Geography of the Voice. 2005.