Perhaps you should try some spelling variations:
"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 _. german book", "a robert j. german book"
"a robert e. hellman book" » "3 robert e. hellman book", "dr robert e. hellman book", "a robust e. hellman book", "a robert _. hellman book", "a robert j. hellman book"
"a robert e. hellman joel" » "3 robert e. hellman joel", "dr robert e. hellman joel", "a robust e. hellman joel", "a robert _. hellman joel", "a robert j. hellman joel"

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 e. hellman joel"))))~.
• 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 e. hellman joel")))).
• 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 e. hellman joel\"))))".
• Removing quotes may allow a broader search: (( a robert e. german book ) or ((( a robert e. hellman book ) OR ( a robert e. hellman joel )))).
• Adding a wildcard symbol may retrieve word variants: (("a robert e. german book") or ((("a robert e. hellman book") OR ("a robert e. hellman joel"))))*.