Perhaps you should try some spelling variations:
20th century » 18th century
reef history » brief history, reeves history, reef fishery
tnf history » motif history, stone history, bief history
imf history » brief history
ref history » brief history, bief history, reform history
etf history » beruf history, ethis history, motif history
21 germany » 11 germany, 20 germany, 7 germany
2f germany » 20 germany, 25 germany, 26 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 (21 germany)) %((((tnf history) OR (((((etf history) OR (ref history))) OR (reef history))))) OR (imf 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 (21 germany)) %((((tnf history) or (((((etf history) OR (ref history))) or (reef history))))) or (imf history)) %2f 20th century%22".
• Adding a wildcard symbol may retrieve word variants: %22agriculture and state %((((2f germany) or (2 germany))) or (21 germany)) %((((tnf history) or (((((etf history) OR (ref history))) or (reef history))))) or (imf history)) %2f 20th century%22*.