Basic text/notes on DNA structure (for non-biologists)
this is a special topic, I'm assuming you have looked over the basic Watson and Crick stuff. 

Maybe closer to your interests DNA does tangle and needs constant maintenance of the amount of winding to keep it properly ordered.  

I would look at topoisomerases and DNA origami to start with. 

Topoisomerases are a class of enzymes that help DNA pack up and wind up into the compact forms of the chromosome when its wound into solenoids in chromatin and unwind into the looser forms when it is loose.  

DNA origami is a field of study which uses DNA as a self assembling template for making three dimensional structures.  

Maybe this helps?  let me know if we can narrow the specifics of your interests.