Torres, J.P., Morales, P., Vidal, J.P. and van Eijck, P. 2013. Simplemail business case: the dilemma of customer portfolio expansion. Estudios de Administración. 20, 2 (Dec. 2013), 63–85. DOI:https://doi.org/10.5354/0719-0816.2013.56394.