David Ellerman, “Translatio versus Concessio: Retrieving the Debate about Contracts of Alienation with an Application to Today’s Employment Contract,” Politics & Society, Vol. 33 No. 3, September 2005, pp. 449-480, http://www.ellerman.org/Davids-Stuff/Econ&Pol-Econ/translatio-v-concessio-P-and-S-final.pdf