APA (7th ed.) Citation

Erlander, S., & Stewart, N. F. (1990). The gravity model in transportation analysis: Theory and extensions. VSP.

Chicago Style (17th ed.) Citation

Erlander, Sven, and Neil F. Stewart. The Gravity Model in Transportation Analysis: Theory and Extensions. Utrecht, Netherlands: VSP, 1990.

MLA (9th ed.) Citation

Erlander, Sven, and Neil F. Stewart. The Gravity Model in Transportation Analysis: Theory and Extensions. VSP, 1990.