Perhaps you should try some spelling variations:
"central american research project epi." » "central americans research project epi.", "central african research project epi.", "central numerical research project epi.", "central america research project epi.", "central american research project ep.", "central american research project e.", "central american research project ed."
"central mode research project sri." » "central model research project sri.", "central more research project sri.", "central modern research project sri.", "central node research project sri.", "central nodes research project sri.", "central body research project sri.", "central mode research project soil.", "central mode research project svp.", "central mode research project series."

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: (("central mode research project sri.") or ("central american research project epi."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("central mode research project sri.") OR ("central american research project epi.")).
• Removing quotes may allow a broader search: (( central mode research project sri. ) or ( central american research project epi. )).
• Adding a wildcard symbol may retrieve word variants: (("central mode research project sri.") or ("central american research project epi."))*.