Providing citations to the work of others you use to create your paper shows that you are using information ethically and honestly. Citing sources gives credit where credit is due and provides readers with a trail of breadcrumbs, which they may use to learn more about your topic and to follow your line of reasoning. Also, citing your sources shows that you have done the work and respect the intellectual property of the people you cite. Each academic discipline tends to have its own separate citation style, often modeled after the core journals in its field.
When publishing for a specific journal, scientists first consult the editorial pages of the intended journal for required style information. For physicists, two dominant styles are generally used: AIP and APS. For this class, your professor recommends APS Style. In this guide, you will want to specifically look at Journal Title Abbreviations on pages 22-26 and Reference Lists on pages 7-8. As you write your paper, you can also use this guide to learn how to construct tables, figures, and mathematical equations.