Perhaps you should try some spelling variations:
"elter national conference" » "elter international conference", "alter national conference", "better national conference", "walter national conference"
"center national conference" » "center international conference", "inter national conference", "centre national conference", "central national conference"
"inter regional science" » "inter national science", "inter regional scale", "unter regional science"

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: (("inter regional science") OR ((("elter national conference") OR ("center national conference")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"inter regional science\") or (((\"elter national conference\") OR (\"center national conference\"))))".
• Removing quotes may allow a broader search: (( inter regional science ) or ((( elter national conference ) OR ( center national conference )))).
• Adding a wildcard symbol may retrieve word variants: (("inter regional science") or ((("elter national conference") OR ("center national conference"))))*.