Zhigeng Pan Jiejie Zhu Weihua Hu Hung Pak Lun Xin Zhou Interactive learning of CG in networked virtual environments. 273-281 2005 29 Computers & Graphics 2 http://dx.doi.org/10.1016/j.cag.2004.12.014 db/journals/cg/cg29.html#PanZHLZ05