Daniel Ortiz-Arroyo (2010) ‘Discovering Sets of Key Players in Social Networks’, in: Abraham, A., Hassanien, A.-E., and Snásel , V. (eds.). ###>Daniel Ortiz-Arroyo (2010) ‘Discovering Sets of Key Players in Social Networks’, in: Abraham, A., Hassanien, A.-E., and Snásel , V. (eds.).