1. Graphics and Graphic Information Processing;Bertin,1981
2. Brewer, C. A. and K. A. Marlow (1993) “Color representation of slope and aspect simultaneously”, Proceedings, Auto-Carto 11, Minneapolis, pp. 328–337.
3. Introductory Cartography;Campbell,1991
4. Cartography: Thematic Map Design;Dent,1993
5. “Opponent process theory and syntax for qualitative relationships in quantitative series”;Eastman;The American Cartographer,1986