Safril, Agus. “CHARACTERISTICS OF RAINFALL AND PRECIPITABLE WATER IN THE ANNUAL AND SEMIANNUAL RAINFALL IN THE AREA WITH VARIOUS INTENSITY OF EL NINO (SUMATERA CASE STUDY)”. Spektra: Jurnal Fisika Dan Aplikasinya, vol. 5, no. 1, Apr. 2020, pp. 41-52, doi:10.21009/SPEKTRA.051.05.