A bibliography (aka "Works Cited," "References," or other) is your list of sources of information. You should include sources from which you quoted, reproduced a figure or other graphic material, AND sources whose information you paraphrased or restated. Each citation in your bibliography should clearly and precisely identify the source you used.
This guide will help you
Citing sources is the hallmark of professional and scholarly communication. As a scientist or engineer, you communicate how you built your work and reached your conclusions. By citing sources, you:
Citing sources encourages you to think. By documenting how others' ideas connect to yours, you get the concepts more firmly in your head. Anything else is cheating yourself on your education.
Plagiarism is bad. Whether you content-scrape, buy another's paper, or just don't keep track of what you're doing, it's a breach of professional ethics if intentional, and also a sign of incompetence if unintentional. Either way, be aware of what constitutes plagiarism, and don't do it.
Each research field has its practice on when to cite a source. You can develop a better understanding of practices in a specific field by reading more. Here are five principles with examples to get you started*.
(All examples used below are from a highly cited article by Staiger, P. et al. ** ) You must cite sources if you:
Besides the above examples, a general principle is when in doubt, cite your sources.
*Princeton University. Academic Integrity at Princeton: When to Cite Sources. https://www.princeton.edu/pr/pub/integrity/pages/cite/ (accessed September 9, 2016).
**Staiger, M. P.; Pietak, A. M.; Huadmai, J.; Dias, G., Magnesium and its alloys as orthopedic biomaterials: A review. Biomaterials 2006, 27 (9), 1728-1734. http://dx.doi.org/10.1016/j.biomaterials.2005.10.003