G. A. H. . Simbolon, N. T. R. . Sitohang, and E. L. . Silalahi, “Comparative Study: Yoga and Pregnancy Exercise on First Stage Pain and Length of Labor in Tapanuli Regency”, jppipa, pendidikan ipa, fisika, biologi, kimia, vol. 9, no. 10, pp. 7950–7957, Oct. 2023.