Perhaps you should try some spelling variations:
"a robert b. german books" » "a robert b. german food", "a robert b. german foods", "dr robert b. german books", "a robust b. german books", "a robot b. german books", "a robert _. german books", "a robert j. german books", "a robert a. german books"
"3 robert e. hermann book" » "3 robert e. hermann broch", "3 robert e. hermann lohr", "3 robert e. hermann von", "dr robert e. hermann book", "3 robert _. hermann book", "3 robert j. hermann book"
"a robert b. german book" » "a robert b. german food", "dr robert b. german book", "a robust b. german book", "a robot b. german book", "a robert _. german book", "a robert j. german book", "a robert a. german book"

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: (("3 robert e. hermann book") OR ((("a robert b. german book") OR ("a robert b. german books"))))~.
• Removing quotes may allow a broader search: (( 3 robert e. hermann book ) or ((( a robert b. german book ) or ( a robert b. german books ))))~.
• Adding a wildcard symbol may retrieve word variants: (("3 robert e. hermann book") or ((("a robert b. german book") or ("a robert b. german books"))))*.