Lalit Garg Sally I. McClean Brian Meenan Peter H. Millard Phase-Type Survival Trees and Mixed Distribution Survival Trees for Clustering Patients' Hospital Length of Stay. 57-72 2011 22 Informatica 1 http://content.iospress.com/articles/informatica/inf22-1-05 db/journals/informaticaLT/informaticaLT22.html#GargMMM11