Your definition for a,reference is correct, but almost everything needs in text citations whether it is a direct quote or not. That includes anything you paraphrased or anything you read related to what you put into your own words. In text citations in style, APA MLA, Harvard style, usually give the last name of the author or authors, initials fir first and middle names, and the year or date if publication. In text citations do not usually give publishers, location of the publishers or page numbers. Web pages should be cited. Movies, television shows, YouTube videos, etc.
How would YOU feel if someone violated YOUR copyright? Pretty angry. Yiu CAN be sued and heavily fined for violating someone's copyright.
You should ask the teacher of this class to explain to you and the class what a citation index is. If the teacher does not know, go to college or university library and ask a reference librarian to show you one and explain how they are used. ©