Since this is not my area of expertise, I searched Google under the key words "sociological perspective on global stratification" to get these possible sources:
Don't just copy the material. Express the ideas in your own words. Although this will take more time and effort, you will learn more.
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.