Veltman, Mark, Robert Kooij, and Sebastian Marban. “Sales Bottlenecks And Their Effect On Profit”. Journal of Applied Business Research (JABR) 30, no. 6 (October 29, 2014): 1725-1738. Accessed March 24, 2019. https://clutejournals.com/index.php/JABR/article/view/8889.