García, F., J. Solano, M. Fuentes, and E. Rubio. 2015. “Detection of the Blood Flow Direction Using Heterodyne Demodulation for a Doppler Ultrasound System and Its Validation by Simulation”. Revista Mexicana De Ingenieria Biomedica 36 (1):23-31. http://rmib.mx/index.php/rmib/article/view/182.