Li, Jinfeng, and Shun Cao. “A Low-Cost Wireless Water Quality Auto-Monitoring System”. International Journal of Online and Biomedical Engineering (iJOE) 11, no. 3 (May 4, 2015): pp. 37–41. Accessed August 20, 2022. https://online-journals.org/index.php/i-joe/article/view/4488.