Perhaps you should try some spelling variations:
heimann books » demand books, german books
hermann books » german books, hermann brochs, hermann broch
robust b » robust _, robust job, robust l1
robust a » robust _, robust cat, robust lca
a robert » 3 robert, dr robert, a robust
robert j » robert _, robert e

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( a ((robust b) OR (robust a)). heimann books ) or ( a robert j. hermann books ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( a ((robust b) OR (robust a)). heimann books ) OR ( a robert j. hermann books )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( a ((robust b) OR (robust a)). heimann books ) or ( a robert j. hermann books ))".
• Adding a wildcard symbol may retrieve word variants: (( a ((robust b) OR (robust a)). heimann books ) or ( a robert j. hermann books ))*.