“…With respect to the inventory models with uncertain demand and shortages, nearly all of the authors assumed that all of the excess demand during the stock-out period become either lost sales [8, 51, 66, 68, 70, 73, 90, 98, 272, 273, 275, 276, 278, 281, 282, 288-290, 294, 296-300, 302, 303, 306, 309-311, 313, 316, 320-322, 326, 332, 335, 337-340], or shortages that are fully backlogged [8,35,112,278,284,286,287,295,297,308,315,319,321,323,325,329,341,343,347]. However, some models with uncertain demand consider a partial backlogging rate: [305,330,331,333] assume that a fixed fraction of shortages are backlogged while [328,342] assume a waiting time function for unmet demand.…”