Perhaps you should try some spelling variations:
goal robert » gal robert, goal poverty
robert e » robert _, robert j
a robust » _ robust
book » books, ebook
eebooks » eebookss, eeebooks
eebookss » eebooksss, eeebookss
ebooks » ebookss, eebooks
heitmann » heimann, heinemann, 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. hermann book ) or ( a robust _. heitmann ((eebooks OR eebookss) or ebooks) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( goal robert e. hermann book ) OR ( a robust _. heitmann ((eebooks OR eebookss) OR ebooks) )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( goal robert e. hermann book ) or ( a robust _. heitmann ((eebooks OR eebookss) or ebooks) ))".
• Adding a wildcard symbol may retrieve word variants: (( goal robert e. hermann book ) or ( a robust _. heitmann ((eebooks OR eebookss) or ebooks) ))*.