Hermann Heinrich Gossen, "The general laws of pleasure and economic value," in The Laws of Human Relations and the Rules of Human Action Derived Therefrom, trans. Rudolph C. Blitz (1983 ), 3-14, 25-39. [And if you have any economics training you should absolutely read the entire text.]
Sergei Podolinsky, "Socialism and the unity of physical forces" (1880).[in class] Irving Fisher, "Mechanical analogies," Mathematical Investigations in the Theory of Value and Prices (1926).
Philip Mirowski, More Heat Than Light: Economics as Social Physics, Physics as Nature's Economics (1989).