Erwinda, Erwinda, et al. “The Linkage of Soil PH, Phosphorus Availability, and Exchangeable Aluminum in Andisol and Recommendations for Soil Improvement”. Jurnal Ilmu Pertanian Indonesia, vol. 30, no. 3, Mar. 2025, pp. 464-72, https://doi.org/10.18343/jipi.30.3.464.