Yulkifli, Y., M. V. Ningrum, and W. Indrasari. “The Validity of Student Worksheet Using Inquiry-Based Learning Model With Science Process Skill Approach for Physics Learning of High School”. Jurnal Penelitian & Pengembangan Pendidikan Fisika, Vol. 5, no. 2, Nov. 2019, pp. 155 -62, doi:10.21009/1.05210.