Villanueva Flores, L., and E. Zelada Leiva. “Personality Characteristics and Some Socio-Cultural and Obstetric Factors in Pregnant Women Diagnosed and Undiagnosed With Hyperemesis Gravidarum”. Revista De Psicología (Trujillo), vol. 5, Dec. 2003, pp. 20-32, http://revistas.ucv.edu.pe/index.php/revpsi/article/view/321.