In the fields of Counseling and Psychology:
Primary Sources: include original research studies or original work generally published in scholarly, peer-reviewed journals and books authored by a researcher or psychological theorist. Literature reviews are NOT primary sources.
Secondary Sources: include literature reviews and books or other sources that summarize and "repackage" another's work.
Tertiary Sources: include encyclopedias and other reference sources that summarize, condense, and define other's work, theories, or ideas.