Perhaps you should try some spelling variations:
2.1 germany » 21 germany, 2017 germany, 9.13 germany
ref history » reef history, brief history, bief history
2f history » imf history, etf history, tnf history
2019 20th » 2019 4th, 2019 6th, 2019 5th
2f 20th » 20 20th, 2.2 20th

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 %2.1 germany %((2f history) OR (ref history)) %((2f 20th) OR (2019 20th)) century%22.
• Adding a wildcard symbol may retrieve word variants: %22agriculture and state %2.1 germany %((2f history) or (ref history)) %((2f 20th) or (2019 20th)) century%22*.