Perhaps you should try some spelling variations:
"harvard world case studies book series." » "harvard cold case studies book series.", "harvard world case studies books series.", "harvard world case studies ebook series."
"harvard world class studies book series." » "harvard cold class studies book series.", "harvard world cass studies book series.", "harvard world cases studies book series.", "harvard world css studies book series.", "harvard world class studies books series.", "harvard world class studies ebook series."

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (("harvard world case studies book series.") OR ("harvard world class studies book series."))~.
• Removing quotes may allow a broader search: (( harvard world case studies book series. ) or ( harvard world class studies book series. ))~.
• Adding a wildcard symbol may retrieve word variants: (("harvard world case studies book series.") or ("harvard world class studies book series."))*.