[Swan et al., 2003]
J. Edward Swan II, Joseph L. Gabbard, Deborah Hix, Robert S. Schulman, and Keun Pyo Kim. A Comparative Study of User Performance in a Map-Based Virtual Environment. In Proceedings of IEEE Virtual Reality 2003, pages 259-266, 2003. (pdf) (bibtex: Swan-2003-ACS).