Isard, Walter (Mayo 1954). «Location Theory and Trade Theory: Short-Run Analysis». Quarterly Journal of Economics68 (2): 305-320. JSTOR1884452. doi:10.2307/1884452.
Capoani, L. (2024). «The gravity equation in international trade: an overview of the introduction of gravity to the study of economics and its systematic barriers». The European Journal of the History of Economic Thought31 (3): 487-520. doi:10.1080/09672567.2024.2329064.
jstor.org
Isard, Walter (Mayo 1954). «Location Theory and Trade Theory: Short-Run Analysis». Quarterly Journal of Economics68 (2): 305-320. JSTOR1884452. doi:10.2307/1884452.