Michael A. Bender Martin Farach-Colton Giridhar Pemmasani Steven Skiena Pavel Sumazin Lowest common ancestors in trees and directed acyclic graphs. 75-94 2005 57 J. Algorithms 2 http://dx.doi.org/10.1016/j.jalgor.2005.08.001 db/journals/jal/jal57.html#BenderFPSS05