Bruce admits it's been a tough summer market.
"We'll still maybe look at another couple to add to the squad," said Bruce. "It's proving very, very difficult. More difficult than it's ever been.
"That's what the challenge is, you've got to find them at the right price and see if they'll come to us.
"Midfield is the area that concerns me most now we've got Sagbo and Graham in. If Sone Aluko stays fit we've got a group of strikers who are a little bit different.
"We're still a bit thin in the middle of the park and that's the area we'll be looking at."