As with any sort of scholarly writing, citing sources of genealogical information in a report, presentation, or other publication is important.
For college assignments, follow the general format of the prescribed format for the course (MLA, APA, Chicago, etc.). Seek help from an instructor, the Writing Center, or a librarian.
This link is to the library guide for Citation Styles.
This link is to a useful on-line article about how to cite sources.