Tom Heskes Jan-Joost Spanjers Wim Wiegerinck EM Algorithms for Self-Organizing Maps. 9-14 2000 IJCNN (6) http://csdl.computer.org/comp/proceedings/ijcnn/2000/0619/06/06196009abs.htm db/conf/ijcnn/ijcnn2000-6.html#HeskesSW00