Secondary sources comment on, collect, review, analyze, explain or interpret primary sources. Remember that not all secondary sources are scholarly.

Discipline	Primary Source	Secondary Source
History	Letters written by a historical figure	A journal article explaining why the letters are important
Literature	A poem	A biography of the author that quotes from the poem as an example of his/her work
Medicine	An empirical study about the effects of physical activity on childhood obesity	A systematic review article about childhood obesity that mentions the study
Kinesiology	An empirical study comparing the lunch function of endurance athletes and bodybuilders	A blog post about what the results of this study means for practicing bodybuilders
Sociology	An interview study where teenagers talked about their use of mobile technology	A news report about the study's findings

What are "secondary sources"?