Perhaps you should try some spelling variations:
20 political » 10 political
11 sources » 2.1 sources, 3 sources, 4 sources
13 sources » 3 sources, 1793 sources, 4 sources
f sources » 3 sources, 4 sources, 5 sources
1 sources » 3 sources

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: %new spain %20 political AND government %2f 18th century %((((f sources) OR (1 sources))) OR (((((11 sources) OR (2 sources))) OR (13 sources))))%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%new spain %20 political and government %2f 18th century %((((f sources) or (1 sources))) or (((((11 sources) OR (2 sources))) or (13 sources))))%22".
• Adding a wildcard symbol may retrieve word variants: %new spain %20 political and government %2f 18th century %((((f sources) or (1 sources))) or (((((11 sources) OR (2 sources))) or (13 sources))))%22*.