SCOUT: A Simple Quadruped that Walks, Climbs and Runs. - Martin Buehler; Robert Battaglia; Anca Cocosco; Geoff Hawker; Joseph Sarkis; Kenneth S. Yamazaki (ICRA, 1998)

Quadruped Trotting with Passive Knees - Design, Control, and Experiments. - Geoff Hawker; Martin Buehler (ICRA, 2000)