N.  Karavas, A. Ajoudani, Tsagarakis, N. G., Saglia, J., Bicchi, A., and Caldwell, D., ?Tele- Impedance based Assistive Control for a Compliant Knee Exoskeleton: Stiffness Augmentation and Motion Assistance?, Robotics and Autonomous Systems, vol. 73 part A, pp. 78-90, 2015 [Online]. Available: http://www.sciencedirect.com/science/article/pii/S0921889014002127

N.  Karavas, A. Ajoudani, Tsagarakis, N. G., Saglia, J., Bicchi, A., and Caldwell, D. G., ?Tele-Impedance based Stiffness and Motion Augmentation for a Knee Exoskeleton Device?, in IEEE International Conference on Robotics and Automation (ICRA2013), 2013, pp. 2194 - 2200 [Online]. Available: 10.1109/ICRA.2013.6630872