Teuvo Kohonen Ilari T. Nieminen Timo Honkela On the Quantization Error in SOM vs. VQ: A Critical and Systematic Study. 133-144 2009 WSOM http://dx.doi.org/10.1007/978-3-642-02397-2_16 conf/wsom/2009 db/conf/wsom/wsom2009.html#KohonenNH09