Perhaps you should try some spelling variations:
"a robert e. hellman book" » "a robert e. hellman joel", "3 robert e. hellman book", "dr robert e. hellman book", "a robust e. hellman book", "a robert j. hellman book"
"a robert _. hellman book" » "a robert _. hellman joel", "3 robert _. hellman book", "dr robert _. hellman book", "a robust _. hellman book"
"a robert e. german book" » "a robert e. german books", "a robert e. german food", "3 robert e. german book", "dr robert e. german book", "a robust e. german book", "a robert j. 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 e. german book") or ((("a robert e. hellman book") OR ("a robert _. hellman book"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("a robert e. german book") OR ((("a robert e. hellman book") OR ("a robert _. hellman book")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"a robert e. german book\") or (((\"a robert e. hellman book\") OR (\"a robert _. hellman book\"))))".
• Removing quotes may allow a broader search: (( a robert e. german book ) or ((( a robert e. hellman book ) OR ( a robert _. hellman book )))).
• Adding a wildcard symbol may retrieve word variants: (("a robert e. german book") or ((("a robert e. hellman book") OR ("a robert _. hellman book"))))*.