Zhiming, Guo, et al. “Shortwave Infrared Hyperspectral Imaging for Detection of PH Value in Fuji Apple”. International Journal of Agricultural and Biological Engineering, vol. 7, no. 2, Apr. 2014, pp. 130-7, https://ijabe.migration.pkpps06.publicknowledgeproject.org/index.php/ijabe/article/view/1219.