Perhaps you should try some spelling variations:
20th century » 18th century
reef history » brief history, reeves history, reef fishery
tnf history » imf history, ref history, motif history
etf history » imf history, ref history, beruf history
2.1 history » 1.1 history, 601 history
2f history » imf history, ref history, 7 history
11 germany » 11 german, 1918 germany, 7 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 %((2 germany) OR (11 germany)) %((((((2f history) OR (tnf history))) OR (2.1 history))) OR (((etf history) OR (reef history)))) %2f 20th century%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%22agriculture and state %((2 germany) or (11 germany)) %((((((2f history) OR (tnf history))) or (2.1 history))) or (((etf history) or (reef history)))) %2f 20th century%22".
• Adding a wildcard symbol may retrieve word variants: %22agriculture and state %((2 germany) or (11 germany)) %((((((2f history) OR (tnf history))) or (2.1 history))) or (((etf history) or (reef history)))) %2f 20th century%22*.