There is no single way to search for ethnographies in Worldcat. Frequently, you will find that names of groups of people, location names, and terms like 'social life', 'customs', 'manners', 'ethnology', and 'ethnography' are often associated with ethnographies, but not always. Try a variety of terms with your searches. E.g. 'Maori Social Life', or 'Amish Ethnography'.