Approximation properties for B-splines with maximal smoothness
S. Takacs

Continuity and convergence in rational triangular Bezier spline based isogeometric analysis
S. Xia, X. Wang and X. Qian

Evaluation of Convergence Rate in Extraordinary Regions for Isogeometric Analysis of Models with Arbitrary Topology
W. Ma, X. Yuan, Y. Ma and M. A Mahmud

Unstructured Spline Spaces for Isogeometric Analysis
G. Sangalli, T. Takacs and R. Vazquez

Manifold-based finite element basis functions of arbitrary order and smoothness
M.  Majeed and F. Cirak