Mechram, Siti, et al. “Nirs Technology (Near Infrared Reflectance Spectroscopy) for Detecting Soil Fertility Case Study in Aceh Province: Review”. Nusantara Science and Technology Proceedings, vol. 1, no. 4, Dec. 2021, pp. 71-75, https://doi.org/10.11594/nstp.2021.1511.