Kaveh Bazargan Gilles Falquet Specifying the Representation of Non-geometric Information in 3D Virtual Environments. 773-782 2009 HCI (2) http://dx.doi.org/10.1007/978-3-642-02577-8_85 conf/hci/2009-2 db/conf/hci/hci2009-2.html#BazarganF09