Herdiman, Herdiman, et al. “The Effect of Progressive Muscle Relaxation on Anxiety in Covid-19 Patients in Bandung ”. Jurnal Keperawatan Komprehensif (Comprehensive Nursing Journal), vol. 8, no. Special Edition, June 2022, https://journal.stikep-ppnijabar.ac.id/jkk/article/view/404.