Exact convergence order of the $L_r$-quantization error for Markov-type   measures
  Let $E$ be a graph-directed set associated with a di-graph $G$. Let $\mu$ be a Markov-type measure on $E$. Assuming a separation condition for $E$, we determine the exact convergence order of the $L_r$-quantization error for $\mu$. This result provides us with accurate information on the asymptotics of the quantization error, especially when the quantization coefficient is infinite. 
Sanguo Zhu, Youming Zhou and Yongjian Sheng
math.MG