There are many reasons why it is so important to cite the sources you use in your research.
APA (American Psychological Association) style is most commonly used in the social sciences.
The style uses in-text citations in the author-date style. For example, (Jones 1998) or if you are using a direct quote (Jones, 1998, p. 199).
Reference List example of a citation from a journal article:
Harlow, H. F. (1983). Fundamentals for preparing psychology journal articles. Journal of Comparative and Physiological Psychology, 55, 893-896.