Akuba, N.H. and Risdiana, N. 2018. Comparison the level of Standard Deviation of N-N interval (SDNN) among Adolescent in Non Smokers and Smokers in Yogyakarta. JKKI : Jurnal Kedokteran dan Kesehatan Indonesia. 9, 1 (Apr. 2018), 30–34. DOI:https://doi.org/10.20885/JKKI.Vol9.Iss1.art6.