Well I don't want you thinking that either. I'm just saying that the authors could mean different things.
Two sources can be SPATIALLY uncorrelated yet have correlated signals applied to them. And they can have uncorrelated signal - ie. time domain and yet be spatially correlated. Mathematically the term correlation means the same thing, but its applied differently and has different implications.
Its hard to explain this without getting into a lot of math - you know five out of four kind of thing.