Perhaps you should try some spelling variations:
a robert » gal robert, a robust
robert j » robert _, robert e
robert b » robert _, robert e
robert a » robert _, robert e
heilmann » heitmann, heinemann, hermann
book » books, ebook
ebooks » ebookss, eebooks, books, ebook
heimann » hermann, heinemann

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