This article is within the scope of WikiProject Maps, a collaborative effort to improve the coverage of Maps and Cartography on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
In section Symbolization you will find 2 references to an image that is not there. The mentioned source Roth, Robert E. "Dot Density Maps." also does not include this. In the PDF it just says "FIGURE 1 HERE". This section sounds like somebody just copied it from somewhere and forgot the images. Where does this come from? 188.8.131.52 (talk) 08:23, 13 May 2011 (UTC)