N. A. S. Suarin, K. S. Chia, and S. F. Z. Mohamad Fuzi, “A Portable in-situ Near-infrared LEDs-based Soil Nitrogen Sensor”, ijie, vol. 10, no. 4, Sep. 2018, Accessed: Aug. 17, 2024. [Online]. Available: https://publisher.uthm.edu.my/ojs/index.php/ijie/article/view/2316