I don't think you need to say 'as previously stated were used' or 'which is again' or any other phrases meaning the same thing. The reader already knows you've said parts of this before.
"the overall objective of the studies conducted was to try and solve the question..."
That sounds fine. Replacing 'solve' with 'answer' might even sound better.
This is probably just personal taste, though. I'm no help if you really want to replace those phrases with other phrases, sorry ^^;;