Xunying Liu Mark John Francis Gales Jim L. Hieronymus Philip C. Woodland Investigation of acoustic units for LVCSR systems. 4872-4875 2011 ICASSP http://dx.doi.org/10.1109/ICASSP.2011.5947447 conf/icassp/2011 db/conf/icassp/icassp2011.html#LiuGHW11