Meiqing, Li, Li Jinyang, Wei Xinhua, and Zhu Wenjing. 2017. “Early Diagnosis and Monitoring of Nitrogen Nutrition Stress in Tomato Leaves Using Electrical Impedance Spectroscopy”. International Journal of Agricultural and Biological Engineering 10 (3):194-205. https://doi.org/10.25165/ijabe.v10i3.3188.