The Effect of Self-Efficacy and Self-Concept on Increasing Optimism in Achieving Targets in Employees of Bank Syariah Indonesia (BSI) Case Study of BSI KCP Medan Aksara . JMB [Internet]. 2024 Aug. 10 [cited 2025 Aug. 27];11(2):985-98. Available from: https://jurnal.fe.umi.ac.id/index.php/JMB/article/view/893