Ariga, R. A.; Amelia, R.; Astuti, S. B.; Fajar, F. A. A.; Ariga, S.; Ariga, H. P. S.; Pane, N. K. Implementation of Lean Six Sigma in Improving Competitive Advantage through Patient Satisfaction and Nurse Resources to Face the Covid-19 Pandemic at USU Medan Hospital. Open Access Maced J Med Sci 2022, 10, 218-222.