Norman E. Fenton Martin Neil Jose Galan Caballero Using Ranked Nodes to Model Qualitative Judgments in Bayesian Networks. 1420-1432 2007 19 IEEE Trans. Knowl. Data Eng. 10 http://doi.ieeecomputersociety.org/10.1109/TKDE.2007.1073 db/journals/tkde/tkde19.html#FentonNC07