Weiming, Cai, et al. “Design of an Experimental Platform to Investigate the Effects of Audible Sounds on Plant Growth”. International Journal of Agricultural and Biological Engineering, vol. 8, no. 5, Oct. 2015, pp. 162-9, https://www.ijabe.migration.pkpps06.publicknowledgeproject.org/index.php/ijabe/article/view/1556.