APA

Frederick Raphael, .Popper. Bogotá, Colombia : Norma, 2000: .

Chicago

Frederick Raphael, .Popper. Bogotá, Colombia : Norma, 2000: .

Harvard

Frederick Raphael, .Popper. Bogotá, Colombia : Norma, 2000: .

MLA

Frederick Raphael, .Bogotá, Colombia : Norma, 2000: . .