Ethnographies are generally accounts of observations or interviews describing specific cultural groups. They're usually published as books. They're not always easy to find in the library because there isn't a specific subject heading to separate them from books that rely on secondary sources.
What if I don't know what what subject headings are or need a refresher?
You can search for ethnographies in Discovery Search using a couple of subject subheadings. Enter a term identifying your culture, location, or nationality, and add one of these keywords or phrases:
Social life and customs
Mixtec (indigenous group) -- Ethnography
Iran -- Social life & customs
For a more in-depth exploration of this strategy, check out "Finding Ethnographies" on the Indiana University Libraries website.
These reference books have articles on most world cultures. Each article contains a bibliography of ethnographies and other works on that culture that you can look for in Discovery Search.