Ramadani, Sri, et al. “Competitive Strategies for Hospitals to Enhance Patient Loyalty at Mahkota Bidadari General Hospital in Langkat Regency, North Sumatra”. Jurnal Indonesia Sosial Sains, vol. 7, no. 6, June 2026, pp. 2701-17, doi:10.59141/jiss.v7i6.2384.