Perhaps you should try some spelling variations:
"a robust b. german books" » "a robust b. german food", "a robust b. german foods", "_ robust b. german books", "a robust a. german books", "a robust job. german books", "a robust l1. german books"
"a robust b. german book" » "a robust b. german food", "_ robust b. german book", "a robust a. german book", "a robust job. german book", "a robust l1. german book"
"a robust _. german book" » "a robust _. german food", "_ robust _. german book"

Try widening your search to All Fields.

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. german book") OR ("a robust _. german book"))) or ("a robust b. german books"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("a robust b. german book") OR ("a robust _. german book"))) OR ("a robust b. german books")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"a robust b. german book\") OR (\"a robust _. german book\"))) or (\"a robust b. german books\"))".
• Removing quotes may allow a broader search: (((( a robust b. german book ) OR ( a robust _. german book ))) or ( a robust b. german books )).
• Adding a wildcard symbol may retrieve word variants: (((("a robust b. german book") OR ("a robust _. german book"))) or ("a robust b. german books"))*.