* Interviews with professionals in the field.
* Job shadowing or internships in the field.
* Informational interviews with friends, family, or acquaintances who work in the field.
* Online or print publications produced by professional organizations or trade publications in the field.
Secondary sources:
* Books, articles, or textbooks about the field.
* Government documents or reports.
* Market research reports.
* Online resources such as blogs, websites, or forums about the field.