One final possibility you may wish to consider is to find research papers on websites that allow students to download academic papers free of charge. Some of the disadvantages include not being able to find exactly what you’re looking for, plus a low quality of work; whilst the primary advantage is that the work is available for free.
Academic Publishing: Free-for-all” - The Economist
paying a publication fee makes a paper available free immediately.
Academic publishing - Wikipedia, the free encyclopedia