Ani, Anthony Ozoemena, Constantine C. Mbajiorgu, Clement Onyeaghala Akubuo, and Peter Azikiwe Onwualu. “Proctor Cone Penetrometer for in-Situ Soil Strength Studies in Nigeria”. International Journal of Agricultural and Biological Engineering 4, no. 3 (September 25, 2011): 16–25. Accessed February 27, 2026. https://ijabe.migration.pkpps06.publicknowledgeproject.org/index.php/ijabe/article/view/465.