Mogens T. Larsen, The Old Assyrian City-State and its Colonies (Copenhagen: Akademisk Forlag, 1976); C.B.F. Walker, “Some Assyrians at Sippar in the Old Babylonian Period,” Anatolian Studies 30 (1980), pp. 15–22; W. F. Leemans, Foreign Trade in the Old Babylonian Period (Leiden: Brill, 1960).