"Yes, we can!": Perceptions of collective efficacy sources in volleyball - Fransen, K.; Vanbeselaere, N.; Exadaktylos, V.; vande Broek, G.; de Cuyper, B.; Berckmans, D.; Ceux, T.; de Backer, M.; Boen, F. (17th Annual Congress of the European College of Sport Science (ECSS), Bruges, 4. -7. July 2012, 2012)