R. Mohammadzadeh,  M. M. Najafizadeh &  M. Nejati. (1970). Buckling of 2D-FG Cylindrical Shells under Combined External Pressure and Axial Compression.
            <i>Advances in Applied Mathematics and Mechanics</i>. <i>5</i> (3).
            391-406.
         doi:10.4208/aamm.2012.m39