Akbar, S., and A. Yudhana. “PROTOTYPE OF TUBE OF LIQUID FERTILIZER BASED QUADCOPTER RIDES FOR RICE LAND PAD”. Jurnal Ecotipe (Electronic, Control, Telecommunication, Information, and Power Engineering), Vol. 3, no. 2, Oct. 2016, pp. 26-30, doi:10.33019/ecotipe.v3i2.22.