http://www.google.com.tr/books?hl=en&lr=&id=mPOWMEEKpY0C&oi=fnd&pg=PR7&dq=racial+classification+in+America&ots=dZdHopM7Q-&sig=9R-ocxzcWgO2PhHGYSEJWz4ATSQ&redir_esc=y#v=onepage&q=racial%20classification%20in%20America&f=false

This is a link to a article by H. Schuman, it is a big book but only the first part, the section of attitudes and norms is quite helpful to understand the concept of "norm". In addition to that on the historical background part it explains the Civil Rights Movements in detail. I read this parts in my previous courses and thought it might be helpful for who wants to read more about race as an issue of society.