Perhaps you should try some spelling variations:
zur sozialgeschichte » zur zeitgeschichte
grey literature » gray literature, greek literature
der literature » der literatur, wider literature, war literature
und text » und texte
text zur » texte zur, text zum, text zu
studien » studies

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

• Performing a fuzzy search may retrieve terms with similar spellings: studien und text zur sozialgeschichte ((der literature) OR (grey literature)) survey~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "studien und text zur sozialgeschichte ((der literature) OR (grey literature)) survey".
• Adding a wildcard symbol may retrieve word variants: studien und text zur sozialgeschichte ((der literature) OR (grey literature)) survey*.