Failing to cite a source correctly is plagiarism. Plagiarism is an academic offense and could get you in serious trouble! But don't panic: as long as you follow the citation guidelines, you will be fine. And remember: when in doubt, cite. It is always better to include a citation that you don't need than to forget a citation that you do need.
Check out our Citing Sources Guide if you need more help!
All biology majors are required to purchase a copy of this book. The library also has a few copies available. This guide contains, among other things, several suggested citation styles.