[Comparative study of Hall's ring and Lippes' loop as intrauterine contraceptives].
D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D007434:Intrauterine Devices / Q000009:adverse effects*; D011247:Pregnancy
Estudio comparativo del anillo de Hall y el asa de Lippes como anticonceptivos intrauterinos.