Svyatskiy, Daniil, and Konstantin Lipnikov. “Second-Order Accurate Finite Volume Schemes With the Discrete Maximum Principle for Solving Richards’ Equation on Unstructured Meshes”. Advances in Water Resources, vol. 104, 2017, pp. 114-26, https://doi.org/10.1016/j.advwatres.2017.03.015.
Painter, Scott L., et al. “Integrated Surface Subsurface Permafrost Thermal Hydrology: Model Formulation and Proof-of-Concept Simulations”. Water Resources Research, vol. 52, no. 8, 2016, pp. 6062-77, https://doi.org/10.1002/2015WR018427.