1. Antenucci, J. C., Brown, K., Croswell, P. L., Kevany, M. J. and Archer, H. (1991) Geographic Information Systems. A Guide to the Technology. Reinhold, New York.
2. Buchanan, H. J. (1992) One man ground survey. In: Geographic Information. The Yearbook of the Association for Geographic Information. Eds. Cadoux-Hudson, J. and Heywood, D. I., Taylor and Francis, London, pp. 262–7.
3. Cain, J. D. (1991) GPS to control counties and municipalities. Proceedings GIS/LIS, Atlanta, pp. 247–56.
4. Coll, D. C. (1991) Developments in equipment and techniques: Microcomputer graphics environment. In: Geographic Information Systems. The Microcomputer and Modern Cartography. Ed. Taylor, D. R. F., Pergamon Press, Oxford, pp. 39–59.
5. Cross, P. A. (1991) GPS for GISs. Mapping Awareness, Vol 5, No 10, pp. 30–4.