Distances between rooted trees Bohdan Zelinka (1991) Mathematica Bohemica Similarity: Two types of a distance between isomorphism classes of graphs are adapted for rooted trees.
On a certain ordering of the vertices of a tree František Neuman (1964) Časopis pro pěstování matematiky Similarity:
The number of isomorphism classes of spanning trees of a graph Bohdan Zelinka (1978) Mathematica Slovaca Similarity: