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

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