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

You may be able to get more results by adjusting your search query.

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