Andayani, Leni, et al. “PENGEMBANGAN ALAT UKUR VISKOSITAS AIR SUNGAI TERCEMAR LIMBAH CAIR BERBASIS SENSOR OPTIK TIPE THROUGH BEAM”. PROSIDING SEMINAR NASIONAL FISIKA (E-JOURNAL), vol. 8, Dec. 2019, pp. SNF2019-PA, doi:10.21009/03.SNF2019.02.PA.04.