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

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