Good guides to the different kinds of citations in each field: APA style is standard in Linguistics and many other social sciences, but MLA style is more common in English Literature.
"a massive central data source and a handy way to graphically compare nations. NationMaster is a vast compilation of data from such sources as the CIA World Factbook, UN, and OECD. Using the form above, you can generate maps and graphs on all kinds of statistics with ease."