@ARTICLE{
        BNmtap08,
        AUTHOR = "B. Bustos and G. Navarro",
        TITLE = "Improving the Space Cost of $k$-NN Search in Metric Spaces 
		 by Using Distance Estimators",
        JOURNAL = "Multimedia Tools and Applications (MTAP)",
        YEAR = "2009",
	PUBLISHER = "Kluwer",
	VOLUME = 41,
	NUMBER = 2,
	PAGES = "215-233"
    }