Perhaps you should try some spelling variations:
"dopnauschwabisches schrifttum heft 1" » "donauschwabisches schrifttum heft 1" (Expand Search), "donauschwabisches christentum heft 1" (Expand Search), "dopnauschwabisches schrifttum heft 3" (Expand Search)
"donauschwabischen schrifttum heft 2" » "donauschwabisches schrifttum heft 2" (Expand Search), "donauschwabisches christentum heft 2" (Expand Search), "donauschwabischen geschichte heft 2" (Expand Search), "donauschwabischen schrifttum heft 3" (Expand Search)

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("dopnauschwabisches schrifttum heft 1") OR ("donauschwabischen schrifttum heft 2"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"dopnauschwabisches schrifttum heft 1\") OR (\"donauschwabischen schrifttum heft 2\"))*".
• Removing quotes may allow a broader search: (( dopnauschwabisches schrifttum heft 1 ) OR ( donauschwabischen schrifttum heft 2 ))*.