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

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: (("dr robert _. heilman book") or ((("a robust e. heilman book") or ("a robust e. hellman joel"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("dr robert _. heilman book") OR ((("a robust e. heilman book") OR ("a robust e. hellman joel")))).
• Removing quotes may allow a broader search: (( dr robert _. heilman book ) or ((( a robust e. heilman book ) or ( a robust e. hellman joel )))).
• Adding a wildcard symbol may retrieve word variants: (("dr robert _. heilman book") or ((("a robust e. heilman book") or ("a robust e. hellman joel"))))*.