See Theorem 1, p. 39, which gives a condition for a d-degenerate graph with a vertex partition based on non-negative integers. There are 40 places in this article where vertex partitions are discussed.
Let P,Q be two partitions of n. Then P is called a refinement of Q if it can be obtained by partitioning some parts of Q. The set of all partitions of n is partially ordered by the refinement relation. Now we can consider either the comparability graph or the Hasse diagram of this poset. Thus, P and Q are adjacent in the comparability graph if (say) P is a refinement of Q, and they are adjacent in the Hasse diagram if, moreover, there is no partition lying properly between them.