Kr. Ivanova, Stefka, et al. “A Review on Dried Blood Spots (DBS) As Alternative, Archival Material for Detection of Viral Agents (Measles, Mumps, Rubella, Hepatitis B Virus)”. American Scientific Research Journal for Engineering, Technology, and Sciences, vol. 30, no. 1, Apr. 2017, pp. 161-72, https://www.asrjetsjournal.org/American_Scientific_Journal/article/view/2804.