Limit cycles and their stability in a passive bipedal gait. - Ambarish Goswami; Bernard Espiau; Ahmed Keramane (ICRA, 1996)

Limit Cycles in a Passive Compass Gait Biped and Passivity-Mimicking Control Laws. - Ambarish Goswami; Bernard Espiau; Ahmed Keramane (Auton. Robots, 1997)