The degree profile of P\'olya trees
  We investigate the profile of random P\'olya trees of size $n$ when only nodes of degree $d$ are counted in each level. It is shown that, as in the case where all nodes contribute to the profile, the suitably normalized profile process converges weakly to a Brownian excursion local time. Moreover, we investigate the joint distribution of the number of nodes of degree $d_1$ and $d_2$ in the levels of the tree. 
Bernhard Gittenberger and Veronika Kraus
math.CO