APA format is the standard citation style for writers and researchers in psychology. The publication manual (updated regularly) provides all the information you need to reference materials in your papers.
Published by the Modern Language Association, the 7th edition of this classic style guide provides students and researchers with important updates on the formatting and style of academic papers. MLA style is widely used in the Humanities (especially Literature, Rhetoric, and Cultural Studies).
The Chicago Style Guide has been published by the University of Chicago Press since 1906. Currently in its 16th edition, the guide provides the comprehensive overview of scholarly writing conventions in history and some social sciences.