Perhaps you should try some spelling variations:
istituzioni politischen » istituzioni politiche, institution politischer, istituzioni politica
storia del » historia del, storia della, storia e
teoria de » teoria della
idee de » idee der, idee des, idee die
de e » de ce, des e, der e

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: ((teoria de) OR (storia del)) idee de e istituzioni politischen*.