1. CARTOGRAPHIC COMMUNICATION
2. An Evaluation of the Use of Grid Squares in Computerised Choropleth Maps
3. Campbell, John (1984). Introductory Cartography (Englewood Cliffs, New Jersey).
4. Cuff, D. S. and Mattson M. T. (1982). Thematic Maps: Their Design and Production (New York, Methuen & Co., Ltd.).
5. Dent, Borden (1985). Principles of Thematic Map Design, (Reading, Mass. Adison-Wesley Publishing Co.).