Universality of intervals of line graph order
  We prove that for every $d\geq 3$ the homomorphism order of the class of line graphs of finite graphs with maximal degree $d$ is universal. This means that every finite or countably infinite partially ordered set may be represented by line graphs of graphs with maximal degree $d$ ordered by the existence of a homomorphism. 
Ji\v{r}\'i Fiala, Jan Hubi\v{c}ka, Yangjing Long
math.CO cs.DM