Perhaps you should try some spelling variations:
"first class classification treatment" » "first class classification assessment", "first class classification trees", "first class classification tree"
"first class classification document" » "first class classification dataset", "first class classification domain", "first class specification document"

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"first class classification document\") OR (\"first class classification treatment\"))".
• Removing quotes may allow a broader search: (( first class classification document ) OR ( first class classification treatment )).
• Adding a wildcard symbol may retrieve word variants: (("first class classification document") OR ("first class classification treatment"))*.