Perhaps you should try some spelling variations:
2.1 germany » 2017 germany, 9.13 germany, 9.14 germany
ref history » reef history, bief history, etf history
21 germany » 11 germany, 2 germany, 20 germany
20 18th » 2017 18th, 2021 18th, 2018 18th

Try widening your search to All Fields.

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: %22agriculture AND state %((21 germany) OR (2.1 germany)) %((ref history) OR (((imf history) OR (brief history)))) %20 18th century%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%22agriculture and state %((21 germany) or (2.1 germany)) %((ref history) or (((imf history) OR (brief history)))) %20 18th century%22".
• Adding a wildcard symbol may retrieve word variants: %22agriculture and state %((21 germany) or (2.1 germany)) %((ref history) or (((imf history) OR (brief history)))) %20 18th century%22*.