International distribution of income: 1960–1987
基于购买力平价和国内收入分布数据，研究发现1960-1987年全球收入高度集中，最富五分之一人口收入是最穷五分之一的三十二倍；中国纳入样本时人均收入不平等下降，排除时上升。
Using recent purchasing power parity-based estimates of national income with intracountry income distribution, this study found the world size distribution of income from 1960 to 1987 to be highly concentrated. In 1987, the wealthiest fifth of mankind received up to thirty-two times the income of the poorest fifth. Per capita income inequality tended to decrease over the twenty-seven year period when China was included in samples and increase when excluded. Of the five third world regions, only East Asia has been closing the per capita income gap with the industrial market countries. Copyright 1992 by WWZ and Helbing & Lichtenhahn Verlag AG