@book{Fromm1989, author = {Erich Fromm}, title = {Del tener al ser bra P{\´o}stuma, 1), Barcelona (Paid{\´o}s Nueva Biblioteca Erich Fromm 3) 2007 [originated 1974-75]}, url = {http://www.planetadelibros.com/del-tener-al-ser-libro-21311.html}, year = {1989}, }