Isard, Walter: Location Theory and Trade Theory: Short-Run Analysis. In: Quarterly Journal of Economics. Band68, Nr.2, Mai 1954, S.305–320, doi:10.2307/1884452, JSTOR:1884452.
L. Capoani: The gravity equation in international trade: an overview of the introduction of gravity to the study of economics and its systematic barriers. In: The European Journal of the History of Economic Thought. 31. Jahrgang, Nr.3, 2024, S.487–520, doi:10.1080/09672567.2024.2329064 (englisch).