Perhaps you should try some spelling variations:
"karl friedrich petersen" » "la friedrich petersen" (Expand Search), "halm friedrich petersen" (Expand Search), "knauer friedrich petersen" (Expand Search)
"karl dietrich petersen" » "kurt dietrich petersen" (Expand Search), "hans dietrich petersen" (Expand Search)
"fur friedrich petersen" » "rub friedrich petersen" (Expand Search), "heer friedrich petersen" (Expand Search), "la friedrich petersen" (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: (((("karl friedrich petersen") OR ("karl dietrich petersen"))) OR ("fur friedrich petersen"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"karl friedrich petersen\") OR (\"karl dietrich petersen\"))) OR (\"fur friedrich petersen\"))*".
• Removing quotes may allow a broader search: (((( karl friedrich petersen ) OR ( karl dietrich petersen ))) OR ( fur friedrich petersen ))*.