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"
"a robert e. hermann book" » "a robert e. hermann broch", "a robert e. hermann lohr", "a robert e. hermann von", "dr robert e. hermann book", "a robust e. hermann book", "a robot e. hermann book", "a robert _. hermann book", "a robert j. hermann book"
"3 robert b. german book" » "3 robert b. german food", "dr robert b. german book", "3 robert _. german book", "3 robert j. german book", "3 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: (("a robert e. hermann book") OR ((("3 robert b. german book") OR ("a robert b. german books"))))~.
• Removing quotes may allow a broader search: (( a robert e. hermann book ) or ((( 3 robert b. german book ) or ( a robert b. german books ))))~.
• Adding a wildcard symbol may retrieve word variants: (("a robert e. hermann book") or ((("3 robert b. german book") or ("a robert b. german books"))))*.