In both theories of galactic formation, top-down and bottom-up, we understand that galaxies become increasingly structured as they age. By increasingly structured, I mean they are more spiral or more elliptical and less amorphous. Since the speed of light is finite, the further you look into space the younger the structures are. This means that there should be a correlation between the focal distance of your telescope and the probability of the galaxies at that depth to have structure. Can I get a simple reference that talks about this and uses real data to make this simple point?
Conselice (2014): "The evolution of Galaxy Structure over time". It's in Annual Reviews of Astronomy and Astrophysics. It's comprehensive and authoritative. Section 4 covers the evolution of morphology with redshift.
I'm not sure what you mean by "increasingly structured". The fraction of spheroidal galaxies is higher now than at high redshifts.