Perhaps you should try some spelling variations:
20th century » 18th century
2.1 history » 1.1 history, 601 history
ref history » reef history, brief history, bief history
etf history » reef history, tnf history, beruf history
imf history » brief history
2.1 germany » 21 germany, 2017 germany, 9.13 germany
2f history » tnf history, 7 history, reef history
2f germany » 20 germany, 21 germany, 25 germany
2 germany » 7 germany, 2 german, 8 germany
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 %((((2f germany) OR (2 germany))) OR (2.1 germany)) %((((((2f history) OR (2.1 history))) OR (imf history))) OR (((etf history) OR (ref history)))) %2f 20th century%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%22agriculture and state %((((2f germany) or (2 germany))) or (2.1 germany)) %((((((2f history) OR (2.1 history))) or (imf history))) or (((etf history) or (ref history)))) %2f 20th century%22".
• Adding a wildcard symbol may retrieve word variants: %22agriculture and state %((((2f germany) or (2 germany))) or (2.1 germany)) %((((((2f history) OR (2.1 history))) or (imf history))) or (((etf history) or (ref history)))) %2f 20th century%22*.