Perhaps you should try some spelling variations:
a robust » _ robust
a robot » _ robot
robot e » robot _, robot 1, robot 5
heilmann » heilemann, heimann, heilman
book » books, ebook
ebooks » ebookss, eebooks
eebooks » eebookss, eeebooks
eebookss » eebooksss, eeebookss
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: (( a robot e. heilmann book ) or ( a robust _. heitmann (ebooks or (eebooks OR eebookss)) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( a robot e. heilmann book ) OR ( a robust _. heitmann (ebooks OR (eebooks OR eebookss)) )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( a robot e. heilmann book ) or ( a robust _. heitmann (ebooks or (eebooks OR eebookss)) ))".
• Adding a wildcard symbol may retrieve word variants: (( a robot e. heilmann book ) or ( a robust _. heitmann (ebooks or (eebooks OR eebookss)) ))*.