Research is a conversation -- we are constantly building off of other's research to contribute to the body of knowledge, refining old theories and creating new ones. But in order to do this, the work you create needs to be accessible; if you don't include citations or if your citations are incorrect, it means people will have a harder time finding the research that influenced you. This disrupts the conversation, so having clear and correct citations is important in furthering research in the field.
A citation is not simply a copied URL or the title of an article. URLs change, and sometimes there are multiple articles with the same title. Having all of the details, including volume, issue and page number can help researchers decipher between similar works with the same title. For most of your assignments at Gonzaga, you will be asked to use APA format, which is a common citation style in the health sciences.
You will need to cite your sources every time you are presenting information that is not an original thought or "common knowledge." Anytime you have to look up information for your paper, you should be inserting a citation. For a literature review, it might feel like you are citing a lot -- that is good! Unless you are writing an essay or describing original research, you should have many citations throughout your paper.