O. B. Kharisma, F. E. Laumal, T. A. Cahyanto, D. Ermayanti Susilo, P. W. Sudarmadji, and . ., “Study of E-mail Data Services based on Delay Tolerant Network in The Riau Province Border Region”, IJET, vol. 7, no. 4.36, pp. 1435–1440, Dec. 2018, doi: 10.14419/ijet.v7i4.36.29002.