JPFA, E. 2019. Introduction, Author Guidlines, and Table of Contents JPFA Vol 9 No 2 December 2019. Jurnal Penelitian Fisika dan Aplikasinya (JPFA). 9, 2 (Dec. 2019), ii-vii. DOI:https://doi.org/10.26740/jpfa.v9n2.pii-vii.