Tackling Cognitively-Complex Collaboration with CoPe_it! - Nikos I. Karacapilidis; Manolis Tzagarakis; Nikos Karousos; George Gkotsis; Vassilis Kallistros; Spyros Christodoulou; Christos Mettouris (Int. J. Web Based Learn. Teach. Technol., 2009)