http://www.google.com.co/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&ved=0CEAQFjAF&url=http%3A%2F%2Ffiles.unicolmayoristas2010.webnode.es%2F200000067-1d6671e605%2FLassalle%2520Ferdinand%2520-%2520Que%2520Es%2520Una%2520Constitucion.PDF&ei=8Go7UL6uBKe36QGQoYGYCQ&usg=AFQjCNHY_FRhI0cZ_dfJvHvEfJkBcaE49g&sig2=RGNUHK8xY0W1uG7080sQjA
