Bernal MSM. Productivity and competitiveness determination of the small-scale mining at the northern mining district in the state of Boyacá. rev. investig. desarro. innov [Internet]. 2013 Feb. 15 [cited 2024 Jun. 30];3(2):72-86. Available from: https://revistas.uptc.edu.co/index.php/investigacion_duitama/article/view/2168