Singh, G. S. (1985). The negative exponential model: A synthesis of rank, gravity, and entropy functions in urban geography. Govind Ballabh Pant Social Science Institute.
Chicago-referens (17:e uppl.)Singh, Govind Saran. The Negative Exponential Model: A Synthesis of Rank, Gravity, and Entropy Functions in Urban Geography. Allahabad: Govind Ballabh Pant Social Science Institute, 1985.
MLA-referens (8:e uppl.)Singh, Govind Saran. The Negative Exponential Model: A Synthesis of Rank, Gravity, and Entropy Functions in Urban Geography. Govind Ballabh Pant Social Science Institute, 1985.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.