American Psychological Association (APA) style is the preferred citation style for your discipline.
The official style guide is only available as a print book: Publication Manual of the American Psychological Association
The APA Style Blog has helpful tips and tricks, but not the full style guide.
Here are a few online resources to help you learn the style. (If you have never used APA citation style before, please take the time to explore the entire site from Purdue OWL).
Please note: While the APA manual provides many examples of how to cite common types of sources, it does not provide rules on how to cite all types of sources. Therefore, if you have a source that APA does not include, APA suggests that you find the example that is most similar to your source and use that format. (Source: Purdue OWL)
You may find this chart on the APA Style blog helpful for creating citations when you are unsure of which rules to use.