Cahyadi, Mokhamad Nur, et al. “ANALISIS NILAI TOTAL ELECTRON CONTENT (TEC) NEAR REAL TIME MENGGUNAKAN DATA GPS DUA FREKUENSI (STUDI KASUS: SURABAYA)”. GEOID, vol. 14, no. 2, Feb. 2019, pp. 56-60, doi:10.12962/geoid.v14i2.1604.