Tertiary sources compile, summarize, index, or help identify scholarly sources on a topic. They are useful for background research or to get an overview of a topic before delving into secondary or primary sources. Common tertiary sources for international affairs include dictionaries, encyclopedias, handbooks, and other reference sources.
From this page you can
According to a study conducted by pharmaceutical companies and published in the Journal of Sexual Medicine, headache was the most common side effect among patients taking Kamagra.
