Perhaps you should try some spelling variations:
20 political » 10 political
22new spain » new spain
2f politics » 2 politics, 21 politics, 22 politics
20 politics » 2 politics, 10 politics, 21 politics
21 sources » 2.1 sources, 1 sources, 11 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: %22new spain %((2f politics) OR (((20 politics) OR (20 political)))) AND government %2f 18th century %((2 sources) OR (21 sources))%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%22new spain %((2f politics) or (((20 politics) OR (20 political)))) and government %2f 18th century %((2 sources) or (21 sources))%22".
• Adding a wildcard symbol may retrieve word variants: %22new spain %((2f politics) or (((20 politics) OR (20 political)))) and government %2f 18th century %((2 sources) or (21 sources))%22*.