It is essential to cite ALL your sources of information when writing an assignment or research project.
There are many different citation styles (APA, Chicago, MLA, etc). Different disciplines use different styles that reflect better the interests of their readers. Generally your professor will let you know which style to use. If your professor has no preference, choose a style yourself and be consistent, use the same style throughout your paper.
The link below provides online examples of citation styles:
For more information on citations check the resource below: