Cita APA (7th ed.)

Conrad, S., & Biber, D. (2001). Variation in English: Multi-dimensional studies. Longman.

Cita Chicago (17th ed.)

Conrad, Susan, i Douglas Biber. Variation in English: Multi-dimensional Studies. Harlow, Eng: Longman, 2001.

Cita MLA (9th ed.)

Conrad, Susan, i Douglas Biber. Variation in English: Multi-dimensional Studies. Longman, 2001.