Subandi, Iga Putri, and Rusly Hidayah. “Validity of Electronic Student Worksheets to Improve Students’ Metacognitive Skills Through PBL on Petroleum Materials”. Hydrogen: Jurnal Kependidikan Kimia, vol. 11, no. 4, Aug. 2023, pp. 391-00, doi:10.33394/hjkk.v11i4.8236.