Perhaps you should try some spelling variations:
"specialist periodical vendors" » "specialized periodicals vendors", "socialism periodicals vendors", "specialist medical vendors", "specialist periodical error", "specialist periodical record"
"specialist periodical sets" » "specialized periodicals sets", "socialism periodicals sets", "specialist medical sets", "specialist periodical set"

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: (("specialist periodical vendors") OR ("specialist periodical sets"))*.
• Removing quotes may allow a broader search: (( specialist periodical vendors ) or ( specialist periodical sets ))*.