Perhaps you should try some spelling variations:
goal robert » gal robert, goal poverty
robert e » robert _, robert j
a robust » _ robust
heilmann » heinemann, hermann, hellman
heimann » hermann, heinemann
book » books
ebook » ebooks
heitmann » heinemann, hermann, hartmann

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( goal robert e. (heilmann or heimann) book ) or ( a robust _. heitmann ebook ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( goal robert e. (heilmann OR heimann) book ) OR ( a robust _. heitmann ebook )).
• Adding a wildcard symbol may retrieve word variants: (( goal robert e. (heilmann or heimann) book ) or ( a robust _. heitmann ebook ))*.