Prayitno, Hadi, et al. “The Effect of Occupational Safety and Health on Work Productivity of Field Workers of Access Network Maintenance at Pt. Telkom Kandatel Jember”. International Journal of Sciences: Basic and Applied Research (IJSBAR), vol. 22, no. 1, May 2015, pp. 257-62, https://www.gssrr.org/JournalOfBasicAndApplied/article/view/3926.