F, H.R. et al. 2021. Self-Empowerment, Affirmation And Relaxation Training Against Stress Levels And Cortisol Levels In Pregnant Women: Systematic Literature Review. STRADA : Jurnal Ilmiah Kesehatan. 10, 1 (May 2021), 335–343. DOI:https://doi.org/10.30994/sjik.v10i1.636.