Perhaps you should try some spelling variations:
"a robust e. hellman book" » "a robust e. hellman joel", "a robust e. german book", "_ robust e. hellman book", "a robust _. hellman book", "a robust a. hellman book", "a robust end. hellman book"
"a robert j. heitmann book" » "3 robert j. heitmann book", "dr robert j. heitmann book", "a robert _. heitmann book", "a robert e. heitmann book"
"a robot _. heitmann book" » "_ robot _. heitmann 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 j. heitmann book") or ("a robot _. heitmann book"))) or ("a robust e. hellman book"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("a robert j. heitmann book") OR ("a robot _. heitmann book"))) OR ("a robust e. hellman book")).
• Removing quotes may allow a broader search: (((( a robert j. heitmann book ) or ( a robot _. heitmann book ))) or ( a robust e. hellman book )).
• Adding a wildcard symbol may retrieve word variants: (((("a robert j. heitmann book") or ("a robot _. heitmann book"))) or ("a robust e. hellman book"))*.