On lengths, areas and Lipschitz continuity of polyharmonic mappings
  In this paper, we continue our investigation of polyharmonic mappings in the complex plane. First, we establish two Landau type theorems. We also show a three circles type theorem and an area version of the Schwarz lemma. Finally, we study Lipschitz continuity of polyharmonic mappings with respect to the distance ratio metric. 
Jiaolong Chen, Antti Rasila, Xiantao Wang
math.CV