“Efek Variasi Waktu dan Jumlah Lilitan pada Sistem Filter Elektromagnetik Terhadap Penurunan Kadar Pb, Zn dan Co: (Effects of Time Variation and Number of Turns in Electromagnetic Filter Systems on Decreasing Levels of Pb, Zn and Co)” (2020) Gravitasi, 19(2), pp. 40–43. doi:10.22487/gravitasi.v19i2.15357.