Perhaps you should try some spelling variations:
german book » german books, german food
gal robert » hall robert
robust end » robust read, robust bound
robert e » robert _, robert j
robust e » robust _, robust a, robust l1
heilman » heilmann, hellman, helman
eeebooks » redbooks, texbooks

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( gal robert e. german book ) or ( _ ((robust e) OR (robust end)). heilman (ebooks or eeebooks) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( gal robert e. german book ) OR ( _ ((robust e) OR (robust end)). heilman (ebooks OR eeebooks) )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( gal robert e. german book ) or ( _ ((robust e) OR (robust end)). heilman (ebooks or eeebooks) ))".
• Adding a wildcard symbol may retrieve word variants: (( gal robert e. german book ) or ( _ ((robust e) OR (robust end)). heilman (ebooks or eeebooks) ))*.