Perhaps you should try some spelling variations:
"a robert _. hartmann book" » "a robert _. hartmann sonke", "a robert _. hartmann von", "dr robert _. hartmann book", "a robust _. hartmann book", "a robot _. hartmann book"
"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 j. hermann book"
"a robert b. german book" » "a robert b. german books", "a robert b. german food", "dr robert b. german book", "a robust b. german book", "a robot b. german book", "a robert j. german book", "a robert a. german book"

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("a robert _. hartmann book") or ((("a robert b. german book") or ("3 robert e. hermann book"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("a robert _. hartmann book") OR ((("a robert b. german book") OR ("3 robert e. hermann book")))).
• Removing quotes may allow a broader search: (( a robert _. hartmann book ) or ((( a robert b. german book ) or ( 3 robert e. hermann book )))).
• Adding a wildcard symbol may retrieve word variants: (("a robert _. hartmann book") or ((("a robert b. german book") or ("3 robert e. hermann book"))))*.