F. A. J. E. Irawan and A. Wahyuni, “Cost And Productivity Analysis Of Installing 40 X 60 X 120 U-Ditches Using Heavy Equipment Compared To Manual Methods In Sumur Welut, Lakarsantri District, Surabaya: Analisis Biaya Dan Produktivitas Pemasangan U-Ditch 40 X 60 X 120 Menggunakan Alat Berat Dibandingkan Metode Manual Di Sumur Welut, Kec. Lakarsantri, Surabaya”, ijins, vol. 27, no. 2, p. 10.21070/ijins.v27i2.2438, Oct. 2026.