Sullón-Cuchupoma, C.L. et al. 2020. Quality of Care and Loyalty of External Users in Peruvian Ophthalmological Centers. Jurnal Ners dan Kebidanan (Journal of Ners and Midwifery). 7, 2 (Aug. 2020), 151–161. DOI:https://doi.org/10.26699/jnk.v7i2.ART.p151-161.