Tips for HathiTrust:
Author = Great Britain : will return documents authored by the government of Great Britain. Similarly, Author = Australia returns Australian government documents, and so on.
Subject = [Place name, e.g. Canada] : will limit your results to books about that place, rather than just mentioning that place somewhere in the text.
Subject = [Topic] : can work well to limit your search to certain genres or topics, such as Travel, Biographies, Politics
Some curated lists of books in HathiTrust:
Magazines of note: