Perhaps you should try some spelling variations:
"harvard world class studies book series." » "harvard world case studies book series.", "harvard world cases studies book series.", "harvard world cost studies book series.", "harvard world class studies from series."
"harvard cold bank study fuel sources." » "harvard cold bank study fuel source.", "harvard world bank study fuel sources.", "harvard bond bank study fuel sources.", "harvard good bank study fuel sources."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("harvard cold bank study fuel sources.") or ("harvard world class studies book series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("harvard cold bank study fuel sources.") OR ("harvard world class studies book series."))*.
• Removing quotes may allow a broader search: (( harvard cold bank study fuel sources. ) or ( harvard world class studies book series. ))*.