On modular forms for some noncongruence subgroups of SL_2(Z) II
  In this paper we show two classes of noncongruence subgroups satisfy the so-called unbounded denominator property. In particular, we establish our conjecture in [KL08] which says that every type II noncongruence character group of Gamma^0(11) satisfies the unbounded denominator property. 
Ling Long, Chris Kurth