Mingchao Cai, Andy Nonaka, John B. Bell, Boyce E. Griffith & Aleksandar Donev. (2020). Efficient Variable-Coefficient Finite-Volume Stokes Solvers.
            <i>Communications in Computational Physics</i>. <i>16</i> (5).
            1263-1297.
         doi:10.4208/cicp.070114.170614a