Perhaps you should try some spelling variations:
"a robust _. heitmann book" » "_ robust _. heitmann book", "a robust _. heimann book", "a robust _. heinemann book", "a robust _. hartmann book", "a robust _. heitmann books", "a robust _. heitmann ebook"
"a robert b. heilmann ebookss" » "3 robert b. heilmann ebookss", "dr robert b. heilmann ebookss", "a robot b. heilmann ebookss", "a robert _. heilmann ebookss", "a robert e. heilmann ebookss", "a robert j. heilmann ebookss", "a robert b. heilmann ebooksss", "a robert b. heilmann eebookss", "a robert b. heilemann ebookss", "a robert b. heimann ebookss", "a robert b. heilman ebookss", "a robert b. heilmann ebooks"

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 _. heitmann book") or ("a robert b. heilmann ebookss"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("a robust _. heitmann book") OR ("a robert b. heilmann ebookss")).
• Removing quotes may allow a broader search: (( a robust _. heitmann book ) or ( a robert b. heilmann ebookss )).
• Adding a wildcard symbol may retrieve word variants: (("a robust _. heitmann book") or ("a robert b. heilmann ebookss"))*.