Scholarly monographs are useful when you need of more in-depth information on a broad topic, e.g. economy in European history. Oftentimes when doing family history research, you may not find a specific article on your ancestor's village or their specific occupation, but you may find some of this information buried in a monograph on a broader topic.
Start by looking specifically: czechoslovakia AND farming; peru AND weaving. This many bring you back results that have both of these words in the description. If this does not work, try to broaden your search. For example: Europe AND economy; Germany AND employment; China AND industrialization. These books may provide additional clues into the lives of your ancestors, but from a broader perspective. They can also provide a road map (references!) for additional sources.
This does not always work, but you might also try typing in a century, or a year, to see if anything appears, e.g. nineteenth-century.
To refine your results for books, under "Type" select Print Books and eBooks.
To find a scholarly monograph, make sure to look at the author (expert, researcher, professor) and the publisher (University or other academic press).
Understanding how immigrants held onto or fought for their own identities in their new land can provide a picture into what they deemed important in their lives. It also provides a picture into the hardships they experienced both prior to and after migration. These books can be integrated with the personal stories that you've collected to provide a broader scope on your ancestor's experiences.
First, you might try browsing this reading list of immigration stories, including non-fiction titles, compiled by the American Library Association: