Piyamongkol, W., & Anantachote, A. (1996). The Study of Correlation between Sound Provoked Test (SPT) and Nonstress Test (NST). Thai Journal of Obstetrics and Gynaecology, 8(4), 295–299. retrieved from https://he02.tci-thaijo.org/index.php/tjog/article/view/92547