Cita APA (7th ed.)

Conrad, S., & Biber, D. (2001). Variation in english: Multi-dimensional studies. Pearson Education.

Cita Chicago (17th ed.)

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

Cita MLA (9th ed.)

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