Efrén Sandoval Hernández He is a research professor at the Northeastern Headquarters of the ciesas (Monterrey). He is a member of the National System of Researchers level 1. His work deals with "border economies" in the region of northeastern Mexico and South Texas. His most recent publication is (2020) "Winning 'clients' and managing favors. Union delegates in Monterrey tianguis", Sociological studies, 40 (118). In 2019 he coordinated (together with Martin Rosenfeld and Michel Peraldi) the book. The northern or southern hemisphere. Global production, cross-border trade and informal markets of used clothing. (Paris: Éditions Pétra / imera / ehess). He has been a professor in different national institutions, and has received funding for his research from national and international institutions.