APA

(1985). Colombia Exporta - Vol.4 No.18,16,14,13. : .

Chicago

1985. Colombia Exporta - Vol.4 No.18,16,14,13. : .

Harvard

(1985). Colombia Exporta - Vol.4 No.18,16,14,13. : .

MLA

Colombia Exporta - Vol.4 No.18,16,14,13. : . 1985.