Perhaps you should try some spelling variations:
20th century » 18th century
ref history » reef history, brief history, bief history
imf history » brief history
etf history » reef history, tnf history, beruf history
21 germany » 11 germany, 20 germany, 7 germany
2f history » tnf history, 7 history, reef history
2 germany » 7 germany, 2 german, 8 germany
20 20th » 90 20th, 2019 20th, 2020 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 %((21 germany) OR (2 germany)) %((((((2f history) OR (ref history))) OR (imf history))) OR (etf history)) %20 20th century%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%22agriculture and state %((21 germany) or (2 germany)) %((((((2f history) OR (ref history))) or (imf history))) or (etf history)) %20 20th century%22".
• Adding a wildcard symbol may retrieve word variants: %22agriculture and state %((21 germany) or (2 germany)) %((((((2f history) OR (ref history))) or (imf history))) or (etf history)) %20 20th century%22*.