Markus Maier Matthias Hein Ulrike von Luxburg Optimal construction of k-nearest-neighbor graphs for identifying noisy clusters. 1749-1764 2009 410 Theor. Comput. Sci. 19 http://dx.doi.org/10.1016/j.tcs.2009.01.009 db/journals/tcs/tcs410.html#MaierHL09