Perhaps you should try some spelling variations:
"first graph sparsification document" » "first graph classification document", "first graph specification document", "first graph clarification document", "first graphs specification document", "first _ sparsification document", "first grand sparsification document"
"first graph modification document" » "first graph specification document", "first graph clarification document", "first graph modification solvent", "first graph classification document", "first grand modification document"
"first grade modification document" » "first grade specification document", "first grade clarification document", "first grade modification solvent", "first graft modification document", "first shade modification document", "first gradient modification document", "first game modification document", "first made modification document", "first decade modification document"

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (("first graph sparsification document") OR ((("first graph modification document") OR ("first grade modification document")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"first graph sparsification document\") or (((\"first graph modification document\") OR (\"first grade modification document\"))))".
• Removing quotes may allow a broader search: (( first graph sparsification document ) or ((( first graph modification document ) OR ( first grade modification document )))).
• Adding a wildcard symbol may retrieve word variants: (("first graph sparsification document") or ((("first graph modification document") OR ("first grade modification document"))))*.