Technical Note - An Algorithm for the p-Median Problem. - Subhash C. Narula; Ugonnaya I. Ogbu; Haakon M. Samuelsson (Oper. Res., 1977)

Lagrangean relaxation and decomposition in an uncapacitated 2-hierarchal location-allocation problem. - Subhash C. Narula; Ugonnaya I. Ogbu (Comput. Oper. Res., 1985)