1. 题目：A Double Squeeze on the Middle Class
   作者：Scott, RH ； Pressman, S
   期刊：JOURNAL OF ECONOMIC ISSUES，  卷: 45   期: 2   页: 333-341    出版年: JUN 2011

2. 题目：Polarization and the decline of the middle class: Canada and the US
   作者：Foster, JE ；Wolfson, MC
   期刊：Journal of Economic Inequality，Volume 8, Number 2 (2010), 247-273。

3. 题目：Social Mobility and Social Inequality: The Ambivalence of the Middle Class
   作者：Wong, YL (Wong, Yi-Lee)
   期刊: SOCIOLOGICAL RESEARCH ONLINE，  卷: 15   期: 2 ,出版年: MAY 24 2010

4. 题目：Falling behind: How rising inequality harms the middle class
   作者：Levy, Frank
   期刊：JOURNAL OF ECONOMIC LITERATURE，  卷: 46   期: 2   页: 425-427   出版年: JUN 2008