Perhaps you should try some spelling variations:
"airports vertical integration series." » "airports regional integration series.", "airports vertical integration theories.", "airports vertical integrating services.", "airports vertical integration schemes.", "airport terminal integration series."
"support state integration series." » "support state integration theories.", "support state integrating services.", "support state integration schemes.", "support system integration series.", "support state interactions series.", "support trade integration series.", "support staff integration series.", "support strategy integration series.", "support estimate integration series."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("airports vertical integration series.") or ("support state integration series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("airports vertical integration series.") OR ("support state integration series.")).
• Removing quotes may allow a broader search: (( airports vertical integration series. ) or ( support state integration series. )).
• Adding a wildcard symbol may retrieve word variants: (("airports vertical integration series.") or ("support state integration series."))*.