M. M. Silva Zambrano, H. A. Romo Romero, J. M. Ramírez Viáfara, and D. M. Galvis Zambrano, “Techniques for detecting voice fundamental frequency in real environments”, ing. Solidar, vol. 13, no. 23, pp. 122–136, Sep. 2017, doi: 10.16925/in.v23i13.2006.