Gerald Holton (4 de diciembre de 2004). «Robert K. Merton - Biographical Memoirs». Proceedings of the American Philosophical Society148 (4): 506-517. Archivado desde el original el 11 de agosto de 2007. Consultado el 7 de agosto de 2007. «He developed a theory of the reference group (i.e., the group to which individuals compare themselves, which is not necessarily a group to which those individuals belong), and elaborated on the concepts of in-group and out-group.»
Gerald Holton (4 de diciembre de 2004). «Robert K. Merton - Biographical Memoirs». Proceedings of the American Philosophical Society148 (4): 506-517. Archivado desde el original el 11 de agosto de 2007. Consultado el 7 de agosto de 2007. «He developed a theory of the reference group (i.e., the group to which individuals compare themselves, which is not necessarily a group to which those individuals belong), and elaborated on the concepts of in-group and out-group.»