Perhaps you should try some spelling variations:
ref history » reef history, brief history, bief history
imf history » brief history
2 germany » 7 germany, 2 german, 5 germany
8 germany » 7 germany
2f 20th » 2.2 20th
20 20th » 90 20th, 2019 20th, 2020 20th

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 germany) OR (((8 germany) OR (1918 germany)))) %((ref history) OR (imf history)) %((2f 20th) OR (20 20th)) century%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%22agriculture and state %((2 germany) or (((8 germany) or (1918 germany)))) %((ref history) or (imf history)) %((2f 20th) OR (20 20th)) century%22".
• Adding a wildcard symbol may retrieve word variants: %22agriculture and state %((2 germany) or (((8 germany) or (1918 germany)))) %((ref history) or (imf history)) %((2f 20th) OR (20 20th)) century%22*.