Haeb-Umbach, Reinhold, and Sven Peschke. “A Novel Similarity Measure for Positioning Cellular Phones by a Comparison With a Database of Signal Power Levels.”10.1109/TVT.2006.889563__IEEE Transactions on Vehicular Technology, vol. 56, no. 1, 2007, pp. 368–72, doi:10.1109/TVT.2006.889563.