1. Bertin J. Graphics and graphic information-processing. Berlin/New York: Walter de Gruyter; 1981.
2. Slocum TA, McMaster RB, Kessler FC, Howard HH. Thematic cartography and geographic visualization. 2nd ed. Upper Saddle River: Pearson-Prentice Hall; 2005.
3. Tufte ER. The visual display of quantitative information. Cheshire: Graphics Press; 1983.