[1] Calabi E. Extremal Kähler metrics[C]//Seminar on Differential Geometry. Annals of Mathematical Studies 102, Princeton:Princeton Univ Press,1982:259-290.
[2] Chen X X. Weak limits of Riemannian metrics in surfaces with integral curvature bound[J]. Calc Var, 1998, 6:189-226.
[3] Chen Q, Chen X X, He W Y. Singular angles of weak limiting metrics under certain integral curvature bounds[J]. Pacific Journal of Mathematics, 2007,231(1):35-49.
[4] Chen X X. Extremal Hermitian metrics on Riemann surfaces[J]. Calc Var, 1999, 8:191-232.
[5] Wang G F, Zhu X H. Extremal Hermitian metrics on Riemann surfaces with singularities[J]. Duke Math Journal, 2000, 104(2):181-210.
[6] Chen Q, Wu Y Y. Character 1-form and the existence of an HCMU metric[J]. Mathematische Annalen, 2011, 351(2):327-345.
[7] Chen Q, Wu Y Y, Xu Bin. On one-dimensional and singular Calabi's extremal metrics whose Gauss curvatures have nonzero umbilical Hessians[J]. Isreal Journal of Mathematics, 2015, 208(1):385-412.