Internal migration and urban employment: comment
指出Cole和Sanders的迁移模型缺乏闭合解，并给出修改建议以提供模型闭合。
Recently in this journal William E. Cole and Richard D. Sanders (1985) criticized the Todaro migration model and offered a different approach. A lively and interesting debate followed but the Cole and Sanders (CS) model was not actually solved. Indeed Michael Todaro...suggested that the model yielded no unique algebraic solution a charge to which CS...did not respond. This [one-page] note identifies the changes needed to provide closure of the CS model. (EXCERPT)