This piece make use of values. Due to the use of lights and darks on the piece, certain lines may have more emphasis than others, thus creating movement in the piece. This piece does not have a subject matter, because it seems to be more focused on formalism due to its wide use of elements and principles of design. This piece does not have content.
The answer to the first question:
"What are some of the best places to find art references?"
I've been drawing for a while, and I find that good references depend on what you're drawing, but if you like to draw people, like I do, I find references for people on Pinterest for one, but I also use real people as references (especially using my siblings :) )
A good way is to see how people work and practice anatomy and proportions, trust me, they are a BIG part of drawing, especially people!!
Hope this helped!! \(^u^\)
P.S. sorry I don't really paint, (cuz I'm bad at it) so I can't really answer that question (^w^')
