Perhaps you should try some spelling variations:
gal robert » hall robert
robert b » robert _, robert e, robert j
a robust » _ robust
heilmann » heilemann, heitmann, heilman
book » books
ebook » ebooks
eebooks » eebookss
ebooks » ebookss
heimann » heinemann

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: (( gal robert b. heilmann (book OR ebook) ) OR ( a robust _. heimann (eebooks OR ebooks) ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( gal robert b. heilmann (book OR ebook) ) or ( a robust _. heimann (eebooks or ebooks) ))~".
• Adding a wildcard symbol may retrieve word variants: (( gal robert b. heilmann (book OR ebook) ) or ( a robust _. heimann (eebooks or ebooks) ))*.