Perhaps you should try some spelling variations:
david robert » davis robert, davies robert, david romer
bates robert » states robert, bos robert, davis robert
a robust » _ robust
heilmann » heilemann, heimann, heitmann
book » books, ebook
redbooks » redbookss, redebooks
heldman » feldman, helpman, hellman

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

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