1. Population-density maps of the United States; techniques and patterns;Alexander;Geographical Review,1943
2. The reliability factor in the drawing of isarithms;Blumenstock;Annals of the Association of American Geographers,1953
3. Isolinienkarten;Imhof;International Yearbook of Cartography,1961
4. Class intervals for statistical maps;Jenks;International Cartographic Yearbook,1963