Manjarrés, C., D. Garizado, M. Obregon, N. Socarras, M. Calle, and C. Jimenez-Jorquera. “Chemical Sensor Network for PH Monitoring”. Journal of Applied Research and Technology, vol. 14, no. 1, Feb. 2016, doi:10.1016/j.jart.2016.01.003.