Efren U. Galapon, and Aloysius J. Aurelio. “Development and Validation of a Competency-Based Learning Package in Plumbing NC II”. The Asian Journal of Education and Human Development (AJEHD), vol. 2, no. 1, Sept. 2021, https://ajehd.unp.edu.ph/index.php/ajehd/article/view/30.