Graphs omitting a bushy tree
Gregory L. Cherlin, N. Shi, Lasse Tallgren · Journal of Graph Theory · 1997
A tree is called bushy if it has no vertex of degree 2. Theorem: the class of countable graphs omitting a fixed finite bushy tree with at least 5 vertices has no universal element. © 1997 John Wiley & Sons, Inc. J Graph Theory 26: 203–210, 1997