Crescencio Bravo Wouter R. van Joolingen Ton de Jong Using Co-Lab to build System Dynamics models: Students' actions and on-line tutorial advice. 243-251 2009 53 Computers & Education 2 http://dx.doi.org/10.1016/j.compedu.2009.02.005 db/journals/ce/ce53.html#BravoJJ09