Citing or documenting the sources used in your research serves two purposes: (1) it gives proper credit to the authors of the materials you used, and (2) it allows those who are reading your work to locate the sources that you have listed as references.
Representing the work of others as your own is plagiarism. See Texas Lutheran University's discussion of "Academic Honesty & Plagiarism" (Student Handbook, p. 6).
Use a citation style approved by your professor.
Visit these pages for citation resources: