Perhaps you should try some spelling variations:
"harvard world class studies ebook series." » "harvard world cass studies ebook series.", "harvard world cases studies ebook series.", "harvard world css studies ebook series.", "harvard world class studies textbook series.", "harvard world class studies yearbook series.", "harvard world class studies bank series.", "harvard world class studies ebooks series."
"harvard cold war studies book series." » "harvard cold war stories book series.", "harvard cold early studies book series.", "harvard world war studies book series.", "harvard cold war studies books series."

You may be able to get more results by adjusting your search query.

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• If you are trying to use Boolean operators, they must be ALL CAPS: (("harvard cold war studies book series.") OR ("harvard world class studies ebook series.")).
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• Adding a wildcard symbol may retrieve word variants: (("harvard cold war studies book series.") or ("harvard world class studies ebook series."))*.