</ref><ref>Karl, A.; W. Muhlnickel & R. Kurth et al. (2004), "Neuroelectric source imaging of steady-state movement-related cortical potentials in human upper extremity amputees with and without phantom limb pain", Pain 110 (1-2): 90-102 | </ref><ref>Karl, A.; W. Muhlnickel & R. Kurth et al. (2004), "Neuroelectric source imaging of steady-state movement-related cortical potentials in human upper extremity amputees with and without phantom limb pain", Pain 110 (1-2): 90-102 |