A class assignment or research paper does not require you to find every possible piece of information on the topic. Your goal is only to identify the "best" possible resources for your topic within the given parameters of the assignment. Things to keep in mind:
Your instructor may ask for scholarly sources, or peer reviewed articles. What's the difference? Are journal articles always peer reviewed? Can I trust an open-access journal I can access without HarvardKey? Are government publications scholarly? Are all resources on Google Scholar scholarly? Although it's beyond the scope of this guide to provide all the answers to these and related questions, keep these things in mind:
There are many different types of sources to consider for your research. One of the important distinctions is between primary and secondary sources. You may be familiar with the examples of a diary, original painting, or any artifact being considered a primary source, while journal articles, movie reviews and the like are often referred to as secondary sources. However, it's a bit more complex than that depending on what kind of discipline/subject area we are talking about.
Here is a guide from the University of Kentucky Libraries that explains some of the different perspectives on these types of resources: