Bachtiar, Harrys, Uki Retno Budihastuti, and Harsono Salimo. 2018. “Biopsychosocial Factors Associated With Preterm Birth at Dr. Moewardi Hospital, Surakarta, Central Java”. Journal of Maternal and Child Health 3 (2):138-45. http://thejmch.com/index.php/thejmch/article/view/94.