Perhaps you should try some spelling variations:
based representation » self representation, data representation, la representation
based presentation » case presentation, brief presentation, late presentation
commercial across » commercial crops, commercial actors, commercial crisis
across course » across sources, across more, across our
east studies » cost studies, peasant studies, event studies

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

• Performing a fuzzy search may retrieve terms with similar spellings: commercial across course ((based presentation) or (based representation)) east studies.~.
• If you are trying to use Boolean operators, they must be ALL CAPS: commercial across course ((based presentation) OR (based representation)) east studies..
• Adding a wildcard symbol may retrieve word variants: commercial across course ((based presentation) or (based representation)) east studies.*.