F. Martínez-Solís, R. Ramírez-Betancour, A. Olmos-López, J. M. Rodríguez-Lelis, A. Claudio-Sánchez, and B. González-Contreras, “Algorithm to estimate the knee angle in normal gait: trajectory generation approach to intelligent transfemoral prosthesis”, Rev Mex Ing Biom, vol. 37, no. 3, pp. 221–233, Sep. 2016.