Perhaps you should try some spelling variations:
a robust » _ robust
robust j » robust _, robert j
robert e » robert _, robert j
heilmann » hermann, hellman, heymann
heitmann » hermann, hartmann
book » books, ebook
eebookss » eebooksss, eeebookss, ebooks
heimann » hermann

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (( a robust j. ((heilmann OR heitmann) OR heinemann) book ) OR ( gal robert e. heimann eebookss ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( a robust j. ((heilmann OR heitmann) or heinemann) book ) or ( gal robert e. heimann eebookss ))~".
• Adding a wildcard symbol may retrieve word variants: (( a robust j. ((heilmann OR heitmann) or heinemann) book ) or ( gal robert e. heimann eebookss ))*.