Perhaps you should try some spelling variations:
"online card research students" » "online card research studies", "online card research instruments", "online card research study", "online care research students", "online based research students", "online car research students", "online call research students"
"online case research instrument" » "online care research instrument", "online use research instrument", "online change research instrument", "online class research instrument", "online classes research instrument"

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: "((\"online case research instrument\") OR (\"online card research students\"))*".
• Removing quotes may allow a broader search: (( online case research instrument ) OR ( online card research students ))*.