Perhaps you should try some spelling variations:
"federal taxes research program series." » "federal taxes research programs series.", "federal taxes research project series.", "federal tables research program series.", "federal tax research program series.", "federal wages research program series.", "federal taxes research programme series.", "federal taxes research programs services."
"central a research program stress." » "central a research programs stress.", "central a research project stress.", "central a research program success.", "central a research program synthesis.", "central 2 research program stress.", "central la research program stress.", "central _ research program stress.", "central 1 research program stress."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("federal taxes research program series.") or ("central a research program stress."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("federal taxes research program series.") OR ("central a research program stress.")).
• Removing quotes may allow a broader search: (( federal taxes research program series. ) or ( central a research program stress. )).
• Adding a wildcard symbol may retrieve word variants: (("federal taxes research program series.") or ("central a research program stress."))*.