%A Van Dung Vu %A Thi Thuy Anh Vu %A Dinh Duc Nguyen %T Nonlinear Response of Axisymmetric Shear Deformable Sigmoid FGM Shallow Spherical Shells Resting on Elastic Foundations under External Pressure %C Hanoi, Vietnam %D 2014 %L SisLab1231