Secondary sources are materials which provide an interpretation, analysis or discussion of information originally presented elsewhere. This is in contrast to primary materials which provide first-hand evidence. What counts as a secondary source depends heavily on the topic you are writing about and the discipline you are working within.
Scholarly articles are a common type of secondary source:
Examples of topics covered in the collection: Organic Farming/Small Farms, School lunch programs, Childhood nutrition, Marketing and advertising, Packaging, Food industry, Environmental impact of GMOs, US food programs during WWI/WWII, Food security, Famine, Vegetarianism, Labor practices, Food safety, Wine making, Obesity, Gender roles through history, Food habits around the world and more.
Depending on your topic, you may find additional useful information in one of the following databases