APA (7. basım) Alıntı

Helgren, D. M., & Sager, R. J. (1995). World geography today. Holt, Rinehart and Winston.

Chicago Style (17. basım) Atıf

Helgren, David M., ve Robert J. Sager. World Geography Today. Austin, TX: Holt, Rinehart and Winston, 1995.

MLA (9th ed.) Atıf

Helgren, David M., ve Robert J. Sager. World Geography Today. Holt, Rinehart and Winston, 1995.