1. Barry, C. Solving the Free Shipping Puzzle. F. Curtis Barry & Company White Paper. Available at: 〈http://www.fcbco.com/articles-whitepapers/solving-the-free-shipping-puzzle.asp〉 (assessed 19.08.2010).
2. Ganeshan, R., Ring, L., Strong, J., 2004. Centralizing Retailing: How much Supply Chain Costs is it Worth?: A Case Study. In: Proceedings of the International Seminar on Production Economics, pp. 139–153.
3. Istobe.com. Weekly Free Shipping List for June 19, 2010. Web: 〈http://istobe.com/free-shipping.html〉 (assessed 19.08.2010).
4. An empirical study of the impact of nonlinear shipping and Handling Fees on Purchase Incidence and Expenditure Decisions;Lewis;Marketing Science,2006
5. The effect of shipping fees on purchase quantity, customer acquisition, and store traffic;Lewis;Journal of Retailing,2006