Kwan, C. S., and F. M. Isa. “The Relationship Between Leadership, Span of Control, Perception of Islamic Products and Services, Perception of Internal Service Quality and the Agents’ Job Satisfaction: A Case of Unit Trust Agents in Johor Bahru”. International Review of Management and Marketing, vol. 6, no. 8S, Dec. 2016, pp. 149-52, https://www.econjournals.com/index.php/irmm/article/view/3925.