1. (k,m)-Catalan numbers and hook length polynomials for plane trees;Du;European J. Combin.,2007
2. A refinement of Cayley’s formula for trees;Gessel;Electron. J. Combin.,2006
3. F. Hivert, J.-C. Novelli, J.-Y. Thibon, Trees, functional equations, and combinatorial Hopf algebras, European J. Combin. (in press)
4. F. Liu, Hook length polynomials for plane forests of a certain type. arXiv:math.CO/0511055
5. Counting Labelled Trees;Moon,1970