Sierra Suárez, L. P., Collazos-Rodríguez, J. A., Sanabria-Domínguez, J., & Vidal-Alejandro, P. (2017). Indicators of Economic Activity: A Review. Apuntes del Cenes, 36(64), 79–107. https://doi.org/10.19053/01203053.v36.n64.2017.5132