Perhaps you should try some spelling variations:
bief history » brief hystory, reef history, brief herstory
ref history » reef history, etf history, tnf history
21 germany » 2.1 germany, 11 germany, 2 germany
2018 18th » 2018 14th, 2018 10th, 2017 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 %((((ref history) OR (bief history))) OR (((imf history) OR (brief history)))) %((2018 18th) OR (2018 15th)) century%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%22agriculture and state %21 germany %((((ref history) or (bief history))) or (((imf history) OR (brief history)))) %((2018 18th) or (2018 15th)) century%22".
• Adding a wildcard symbol may retrieve word variants: %22agriculture and state %21 germany %((((ref history) or (bief history))) or (((imf history) OR (brief history)))) %((2018 18th) or (2018 15th)) century%22*.