J. Aubin, Viability Theory, Birkhäuser, 1991.
DOI : 10.1007/978-0-8176-4910-4
URL : https://hal.archives-ouvertes.fr/inria-00636570

B. Brogliato, Nonsmooth Impact Mechanics, 1996.
DOI : 10.1007/978-1-4471-0557-2

Y. Fujimoto, S. Obata, and A. Kawamura, Robust biped walking with active interaction control between foot and ground, Proceedings. 1998 IEEE International Conference on Robotics and Automation (Cat. No.98CH36146)
DOI : 10.1109/ROBOT.1998.680613

F. Genot and B. Espiau, On the control of the mass center of legged robots under unilateral constraints, Proc. of the First International Symposium on Mobile, Climbing and Walking Robots CLAWAR'98

J. Pratt and G. Pratt, Intuitive control of a planar bipedal walking robot, Proceedings. 1998 IEEE International Conference on Robotics and Automation (Cat. No.98CH36146)
DOI : 10.1109/ROBOT.1998.680611

C. Samson, M. L. Borgne, and B. Espiau, Robot Control: The Task Function Approach, 1991.

J. Yamaguchi, A. Takanashi, and I. Kato, Development of a biped walking robot compensating for three-axis moment by trunk motion, Proceedings of 1993 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS '93)
DOI : 10.1109/IROS.1993.583168