You could start by looking at some of the links from this Google (it was a search for only .edu sites) https://www.google.com/search?hl=en&as_q=middle+class&as_epq=&as_oq=&as_eq=&as_nlo=&as_nhi=&lr=&cr=&as_qdr=all&as_sitesearch=.edu&as_occt=any&safe=images&tbs=&as_filetype=&as_rights=#as_qdr=all&hl=en&lr=&q=is+there+a+middle+class+site:.edu That may give you a little background info. From there try using our Sociology Research Guidehttp://libguides.starkstate.edu/sociology and use the database on the left side called SocINDEX to locate research articles on your topic.