Perhaps you should try some spelling variations:
"resource research theory" » "resources research theory", "source research theory", "resonance research theory", "resource research through"
"resource search theory" » "resource sears theory", "resource scarce theory", "source search theory"

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"resource research theory\") OR (\"resource search theory\"))".
• Removing quotes may allow a broader search: (( resource research theory ) OR ( resource search theory )).
• Adding a wildcard symbol may retrieve word variants: (("resource research theory") OR ("resource search theory"))*.