Perhaps you should try some spelling variations:
2017 germany » 20 germany, 17 germany, 2006 germany
reef history » brief history, reeves history, reef fishery
20th century » 18th century
2.1 germany » 21 germany, 9.13 germany, 9.14 germany
ref history » brief history, bief history, etf history
imf history » brief history
2f history » etf history, tnf history, 7 history
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) OR (2017 germany)) %((((((2f history) OR (reef history))) OR (ref history))) OR (imf history)) %2f 20th century%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%22agriculture and state %((2.1 germany) OR (2017 germany)) %((((((2f history) or (reef history))) or (ref history))) or (imf history)) %2f 20th century%22".
• Adding a wildcard symbol may retrieve word variants: %22agriculture and state %((2.1 germany) OR (2017 germany)) %((((((2f history) or (reef history))) or (ref history))) or (imf history)) %2f 20th century%22*.