Abanavaz, Fezzeh, and Morteza Khakzar Bafruei. “Studying a Two-Level Supply Chain Including a Manufacturer and Several Retailers With a Wholesale Price Contract Between Them”. International Review of Management and Marketing, vol. 10, no. 5, Oct. 2020, pp. 165-71, https://econjournals.org.tr/index.php/irmm/article/view/8402.