Increasingly, scholars are frustrated that their research is available only to people who have access to big libraries, so they either publish their research in journals that are free to anyone to read or they reserve the right to put copies of their research online. Try Googling the author and title of an article you need and add filetype:pdf - you might get lucky and find a free copy online.
For research in biology and biomedical sciences, the National Institutes of Health provides two nifty options. PubMed is a huge database of medical research articles. After you do a search, you can choose to limit your results to free full text articles.
Or you can go to PubMed Central, an archive of over 1,000 life science journals and articles based on research funded by the NIH to find lots of articles in biology and medicine.
As you decide which sources to look at more closely think about these ideas.
Be sure you do some skimming before you print anything off or haul books back to your dorm room. Quite often, a source that seems to be exactly on your topic turns out to be not very helpful after all. You don't want to discover that when you're sitting down to write a paper that's due tomorrow.
Quite often you will be expected to use "scholarly" or "peer-reviewed" sources. How can you tell whether a source is scholarly? Look for these indicators.
Though many databases let you limit a search to scholarly articles, those limiters aren't foolproof. As an example, they will include book reviews, which are not reporting original research. Take a look at "Anatomy of a Scholarly Article" from North Carolina State University Library.
One of the reasons Gustavus requires at least one Writing in the Disciplines (WRITD) courses is because styles are different for in different majors. Scholarly sources do not all look the same. Scholarly articles in history are usually longer than those in physics journals. Articles in chemistry often have color illustrations and their journals carry advertising, but you won't find many color illustrations or advertisements in literary criticism journals. In sociology and psychology, articles almost always have abstracts, but you rarely see them in art history or religion articles. Though they look different, all fundamentally are the work of scholars reporting their findings to extend what we know about the world.
When you have an article with references, you can see if a particular reference is available by looking the journal's name up at the link below. Then you can use the volume and date information to navigate to the article. If we don't have access to that journal, we usually can get it from another library.