Las empresas mas productivas se autoseleccionan para exportar? Aplicacion de una prueba para el caso de Portugal.
Armando Silva, Óscar Afonso, Ana Paula Africano
Investigación Económica, vol. 72, 2013, p. 135-161.

Learning-by-Exporting: What We Know and What We Would Like to Know
Óscar Afonso, Armando Silva, Ana Paula Africano
International Trade Journal, vol. 26, 2012, p. 255-288.

Which Manufacturing Firms Learn by Exporting?
Armando Silva, Óscar Afonso, Ana Paula Africano
Journal Of International Trade And Economic Development, vol. 21, 2012, p. 773-805.