Perhaps you should try some spelling variations:
gail robert » gal robert, hall robert, ball robert
robert j » robert _, robert e
a robust » _ robust
robust e » robust _, robust a, robust end
book » books
ebook » ebooks
ebooks » ebookss, books, redbooks, texbooks
heilmann » heilemann, heimann, heilman

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( gail robert j. heitmann (book OR ebook) ) or ( a robust e. heilmann ebooks ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( gail robert j. heitmann (book OR ebook) ) OR ( a robust e. heilmann ebooks )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( gail robert j. heitmann (book OR ebook) ) or ( a robust e. heilmann ebooks ))".
• Adding a wildcard symbol may retrieve word variants: (( gail robert j. heitmann (book OR ebook) ) or ( a robust e. heilmann ebooks ))*.