Perhaps you should try some spelling variations:
heilman book » german book
heimann book » german book
hermann book » german book, hermann broch, hermann lohr
a robert » 3 robert, dr robert, a robot
robert e » robert j
a robust » _ robust
robust e » robust _, robust a, robust end

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

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