Perhaps you should try some spelling variations:
research instruments » research instrument, research instrumentation, research environments
research documents » search document, research arguments, research comments
handel research » channel research, panel research, hanse research
online rand » online brand, online band, online random
online hand » online band, online brand, online hate

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: (( online handel research documents ) OR ( ((online rand) OR (online hand)) research instruments )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( online handel research documents ) or ( ((online rand) OR (online hand)) research instruments ))".
• Adding a wildcard symbol may retrieve word variants: (( online handel research documents ) or ( ((online rand) OR (online hand)) research instruments ))*.