Perhaps you should try some spelling variations:
sozialgeschichte grey » sozialgeschichte der, sozialgeschichte des
zur sozialgeschichte » zur zeitgeschichte
grey literature » gray literature, greek literature
und tests » und trusts, und texte, und text
tests zur » tests fur, tests auf, tests per

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (studien or studies) und tests zur sozialgeschichte grey literature ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (studien OR studies) und tests zur sozialgeschichte grey literature ;.
• Adding a wildcard symbol may retrieve word variants: (studien or studies) und tests zur sozialgeschichte grey literature ;*.