Buppasiri, P., and S. Chaisitt. “Incidence of Positive VDRL in the Second Antenatal Screening for Syphilis at Srinagarind Hospital, Khon Kaen University”. Srinagarind Medical Journal, vol. 24, no. 4, Nov. 2013, pp. 292-5, https://li01.tci-thaijo.org/index.php/SRIMEDJ/article/view/13036.