Niklas Elmqvist Mihail Eduard Tudoreanu Philippas Tsigas Evaluating motion constraints for 3D wayfinding in immersive and desktop virtual environments. 1769-1778 2008 CHI http://doi.acm.org/10.1145/1357054.1357330 conf/chi/2008 db/conf/chi/chi2008.html#ElmqvistTT08