Perhaps you should try some spelling variations:
gail robert » gal robert, dahl robert, marill robert
ball robert » bill robert, ballon robert, cull robert
hall robert » cull robert, gal robert, thiel robert
robert e » robert _, robert j
heilmann » heilemann, heimann, heilman
book » books, ebook
texbooks » texbookss, texebooks, textbooks, textbook, redbooks

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) OR (ball robert)) j. heilmann book ) or ( hall robert e. heitmann texbooks ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( ((gail robert) OR (ball robert)) j. heilmann book ) OR ( hall robert e. heitmann texbooks ))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( ((gail robert) OR (ball robert)) j. heilmann book ) or ( hall robert e. heitmann texbooks ))*".