1. The Enumeration of Labelled 2-Trees;Beineke;Notices Amer. Math. Soc.,1968
2. On the Number of k-Dimensional Trees;Beineke;J. Combinatorial Theory,1969
3. A Theorem on Trees;Cayley;Quart. J. Math.,1889
4. On Cayley's Formula for Counting Trees;Clarke;J. London Math. Soc.,1958
5. Mutual Choices;Göbel;Stichtung Math. Centrum Amsterdam,1967