In academic writing, it is important for you to keep the same formatting and citations throughout your paper. This will allow your readers to easily see your sources, understand your argument, and to not get distracted from unnecessary formatting like weird fonts and large indents.
It is also very important that you avoid using Plagiarism. Plagiarized works, even accidental, would constitute a failed grade for the assignment, and even could result in academic suspension or expulsion from the school. Sticking with the correct citations is the safest and easiest way to avoid plagiarism.
There are several different styles to choose from when citing your work. Most often, your professor will let you know which style to use. Different styles also are used my the different disciplines. The most common styles are: