Perhaps you should try some spelling variations:
barnett robert » barner robert, bassett roberta
hermann books » hermann brochs, hermann broch, demand books
german books » german book, german food
robert e » robert _, robert j
a robust » _ robust
heilman » heilmann, hellman, helman
eeebooks » redbooks, ebooks, texbooks

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( barnett robert e. ((hermann books) or (german books)) ) or ( a robust _. heilman eeebooks ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( barnett robert e. ((hermann books) OR (german books)) ) OR ( a robust _. heilman eeebooks )).
• Adding a wildcard symbol may retrieve word variants: (( barnett robert e. ((hermann books) or (german books)) ) or ( a robust _. heilman eeebooks ))*.