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