David M. Blei Thomas L. Griffiths Michael I. Jordan Joshua B. Tenenbaum Hierarchical Topic Models and the Nested Chinese Restaurant Process. 2003 conf/nips/2003 NIPS http://books.nips.cc/papers/files/nips16/NIPS2003_AA03.pdf db/conf/nips/nips2003.html#BleiGJT03