A.  Bicchi, Prattichizzo, D., and Melchiorri, C., ?Force and Dynamic Manipulability for Cooperating Robot Systems?, in Proc. IEEE/RSJ Int. Conf. on Intelligent Robots and Systems, 1997. 

A.  Bicchi, Melchiorri, C., and Balluchi, D., ?On the Mobility and Manipulability of General Multiple Limb Robotic Systems?, IEEE Trans. Robotics and Automation, vol. 11, pp. 215-228, 1995. 

A.  Bicchi and Melchiorri, C., ?Mobility and Kinematic Analysis of General Cooperating Robotic Systems?, in Proc. IEEE Conf. on Robotics and Automation, 1992, pp. 421-426.