Manabu Kuroki Zhihong Cai Hiroki Motogaito The Graphical Identification for Total Effects by using Surrogate Variables. 340-345 2005 conf/uai/2005 UAI http://uai.sis.pitt.edu/displayArticleDetails.jsp?mmnu=1&smnu=2&article_id=1191&proceeding_id=21 db/conf/uai/uai2005.html#KurokiCM05