Perhaps you should try some spelling variations:
crop adoption » crop adaptation
erp adoption » early adoption, die adoption, 10 adoption
era adoption » ema adoption, esa adoption, a adoption
der adoption » user adoption, die adoption
energy crop » energy crops
energy erp » energy era, energy ep, energy erec

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: "\"((((\\"energy crop adoption\\") or (\\"energy erp adoption\\"))) or (\\"energy ((era adoption) OR (der adoption))\\"))\"".
• Removing quotes may allow a broader search: (((( energy crop adoption ) or ( energy erp adoption ))) or ( energy ((era adoption) OR (der adoption)) )).