Lions, J.-L., R. Temam, and S. Wang. “Geostrophic Asymptotics of the Primitive Equations of the Atmosphere”. Topological Methods in Nonlinear Analysis, vol. 4, no. 2, Dec. 1994, pp. 253-87, https://apcz.umk.pl/TMNA/article/view/TMNA.1994.030.