Online Research
Searching the web for assignments and/or tests can be tricky, as you always have to question the credibility of your source. If you have a hard time finding reliable sources, often times you can go online and search subjects or topics on university websites, and even college websites. 9/10, the information is accurate and you will have no trouble applying it to your studies.
If you had no luck with finding what you were looking for there, you can always try one of the following websites:
https://academic.microsoft.com/
https://www.researchgate.net/search
If none of the above listed cites helped, you can always try other options.
Library
When doing research, your most reliable option is the library. With dozens, if not hundreds of available options, the chances of finding the right book for your specific subject is very likely.
Friends & Family
When in doubt, or looking for help, you can always go to a person who might have some knowledge on what you are studying. 
A friend in your class, or maybe on older sibling, if not mom or dad. Resources are everywhere, and it is up to you if you want to use them or not.
Old Tests
Looking through old tests or assignments is always a good idea, as it shows you what you already know, and also shows you what you need to learn a little more about. Getting a bad grade is an awful feeling, but at least it shows you what you’ve got down to the core, and gives you the option to better yourself and knowledge for the next assignment.
Study Smart 