Perhaps you should try some spelling variations:
"a robert j. german book" » "a robert j. german books", "a robert j. german food", "3 robert j. german book", "dr robert j. german book", "a robot j. german book", "a robert _. german book", "a robert e. german book"
"a robert j. heilman book" » "3 robert j. heilman book", "dr robert j. heilman book", "a robot j. heilman book", "a robert _. heilman book", "a robert e. 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"

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. heilman book") OR ("a robert j. german book"))) or ("a robust e. hellman joel"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("a robert j. heilman book") OR ("a robert j. german book"))) OR ("a robust e. hellman joel"))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"a robert j. heilman book\") OR (\"a robert j. german book\"))) or (\"a robust e. hellman joel\"))*".
• Removing quotes may allow a broader search: (((( a robert j. heilman book ) OR ( a robert j. german book ))) or ( a robust e. hellman joel ))*.