APA Style

Purba, E. et al (2012). The Salivary Estriol Level was Higher in Preterm Delivery Compared to that in Preterm Pregnancy . Jakarta: Indonesian Society of Obstetrics and Gynecology.

MLA Style

Purba, Erwin. et al. "The Salivary Estriol Level was Higher in Preterm Delivery Compared to that in Preterm Pregnancy". Jakarta: Indonesian Society of Obstetrics and Gynecology, 2012. Text.