Xie, Chuanqi, Ce Yang, Alexander Hummel Jr, Gregg A Johnson, and Forrest T Izuno. 2018. “Spectral Reflectance Response to Nitrogen Fertilization in Field Grown Corn”. International Journal of Agricultural and Biological Engineering 11 (4). Beijing, China:118-26. https://www.ijabe.org/index.php/ijabe/article/view/2960.