Fitrie, N., Yusgunawan, E., Ichsan, R.N. and Siregar, B.A. 2026. THE SYNERGY OF LEADERSHIP AND ORGANIZATIONAL BEHAVIOR ON MARKETING MANAGEMENT EFFECTIVENESS: A CASE STUDY ON SMES IN NORTH SUMATRA. Journal of Sustainable Business, Economics and Accounting. 1, 1 (Feb. 2026), 13-22. DOI:https://doi.org/10.47652/mjeb.v1i1.893.