Afriliyanti, R., S. Yusnaini, A. Karyanto, D. Hapsoro, A. Niswati, and M. Utomo. “Effect of Long-Term Tillage and Nitrogen Fertilization Residue on Soil Biochemical Properties and Cowpea Yield”. JOURNAL OF TROPICAL SOILS, vol. 26, no. 3, Sept. 2021, pp. 141-7, doi:10.5400/jts.2021.v26i3.141-147.