@Book{RANME20161006123, title = "La natalidad dirigida", author = "Fern\'{a}ndez-Ruiz, C\'{e}sar, 1906-1966", publisher = "Madrid : Plus Ultra, cop. 1952", editor = "Plus Ultra, cop. 1952", URL = "http://bibliotecavirtual.ranm.es/ranm/es/consulta/registro.do?id=2612", year = "1956", }