The emergence of the cortizol circadian rhythm in monozygotic and dizygotic twin infants: the twin-pair synchrony - Custódio, Rodrigo José; Martinelli Júnior, Carlos Eduardo; Milani, Soraya Lopes Sader; Simões, Aguinaldo Luiz; Castro, Margaret de; Moreira, Ayrton Custódio (Clinical Endocrinology, 2007)