Thiyagarajan, R., et al. “Performance Evaluation of Cone Penetrometer Device for Measuring the Subsoil Compaction in Mulched Plots”. International Journal of Agricultural and Biological Engineering, vol. 6, no. 3, Sept. 2013, pp. 19-27, https://www.ijabe.migration.pkpps06.publicknowledgeproject.org/index.php/ijabe/article/view/707.