A background source provides important context about your Object of Study. As you start your research, what information do you already know about your topic? What information would be useful to know? Encyclopedias and dictionaries are good sources to consult when you are at the beginning of your research and you are compiling the basics about your topic. Also, search the catalog for books on your topic that can provide a detailed history of it.
An analysis source (or argument source) contain claims that allow the author to engage with the topic. A claim is information that agrees with, disputes, refines, or furthers an idea. You can find analysis in scholarly or peer reviewed articles, which can be found in a journal database. Below are databases to try.
Academic Search Ultimate offers access to an unprecedented collection of resources including journals, magazines, reports, books, and videos. Many are peer-reviewed and full-text. Subjects range from astronomy to zoology.