Παραπομπή σε μορφή APA (7η εκδ.)

Bernal, M. S. M. (2013). Productivity and competitiveness determination of the small-scale mining at the northern mining district in the state of Boyacá. Universidad Pedagógica y Tecnológica de Colombia.

Παραπομπή σε μορφή Chicago (17η εκδ.)

Bernal, Martha Stella Martínez. Productivity and Competitiveness Determination of the Small-scale Mining at the Northern Mining District in the State of Boyacá. Universidad Pedagógica y Tecnológica de Colombia, 2013.

Παραπομπή σε μορφή MLA (9th εκδ.)

Bernal, Martha Stella Martínez. Productivity and Competitiveness Determination of the Small-scale Mining at the Northern Mining District in the State of Boyacá. Universidad Pedagógica y Tecnológica de Colombia, 2013.