Perhaps you should try some spelling variations:
commercial crops » commercial code, commercial credit, commercial banks
based reflective » based selective, based reflections, based receptive
earlier studies » early studies
care studies » case studies, career studies, scale studies
crops space » across space, europe space, porous space
space based » place based

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: commercial crops space based reflective ((care studies) OR (earlier studies)).~.
• Adding a wildcard symbol may retrieve word variants: commercial crops space based reflective ((care studies) or (earlier studies)).*.