Perhaps you should try some spelling variations:
gail robert » gal robert, davis robert, blair robert
robert j » robert _, robert e
a robust » _ robust
robust e » robust _, robert e
heitmann » heimann, hermann, hartmann
heilmann » heimann, hermann, hellman
ebookss » ebooks

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