To identify potential sources for relevant articles, start with identifying potential stakeholders. Consider who might have an interest in your topic and which disciplines represent them. Depending upon your topic, there could be multiple stakeholder representing a variety of disciplines. For example, the topic of taxing sweetened beverages (i.e., "soda tax") would have multiple stakeholders representing a range of disciplines, including nutrition, public health, economics, legal studies, etc.
Once you identify potential stakeholders,you can then locate the resources that contain the literature for the disciplines that represent them. Be prepared to look beyond biomedical databases for topics that cross into disciplines such as sociology,technology, the environment, economics, and the law. Searching multidisciplinary databases, such as Scopus and Web of Science, makes sense for topics that have multiple stakeholders.
To learn more about identifying potential stakeholders, check out:
Identifying and Analyzing Stakeholders and Their Interests
Work Group for Community Health and Development at the University of Kansas.