Perhaps you should try some spelling variations:
"a robert _. hartmann book" » "a robert _. hartmann sonke", "a robert _. hartmann von", "3 robert _. hartmann book", "dr robert _. hartmann book", "a robust _. hartmann book"
"a robert b. hermann book" » "a robert b. german book", "a robert b. hermann broch", "a robert b. hermann lohr", "3 robert b. hermann book", "dr robert b. hermann book", "a robust b. hermann book", "a robert j. hermann book", "a robert a. hermann book"
"a robert e. hermann book" » "a robert e. german book", "a robert e. hermann broch", "a robert e. hermann lohr", "3 robert e. hermann book", "dr robert e. hermann book", "a robust e. hermann book", "a robert j. hermann 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. hermann book") or ("a 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. hermann book") OR ("a robert e. hermann book")))).
• Removing quotes may allow a broader search: (( a robert _. hartmann book ) or ((( a robert b. hermann book ) or ( a robert e. hermann book )))).
• Adding a wildcard symbol may retrieve word variants: (("a robert _. hartmann book") or ((("a robert b. hermann book") or ("a robert e. hermann book"))))*.