Shuang Tan,  Wenjun Sun,  Kun Xu,  Junxia Wei &  Guoxi Ni. (2020). Time Implicit Unified Gas Kinetic Scheme for 3D Multi-Group Neutron Transport Simulation.
            <i>Communications in Computational Physics</i>. <i>28</i> (3).
            1189-1218.
         doi:10.4208/cicp.OA-2019-0050