Perhaps you should try some spelling variations:
"a robust b. heilman book" » "_ robust b. heilman book", "a robust b. heilmann book", "a robust b. hellman book", "a robust b. heitmann book", "a robust b. heilman books", "a robust b. heilman ebook"
"a robust _. heilman book" » "_ robust _. heilman book", "a robust _. heilmann book", "a robust _. hellman book", "a robust _. heitmann book", "a robust _. heilman books", "a robust _. heilman ebook"
"a robert b. heilman book" » "gal robert b. heilman book", "a robert _. heilman book", "a robert e. heilman book", "a robert j. heilman book", "a robert b. heilmann book", "a robert b. hellman book", "a robert b. heitmann book", "a robert b. heilman books", "a robert b. heilman ebook"

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