Naumann, J. “Degenerate Parabolic Problems in Turbulence Modelling”. Bullettin of the Gioenia Academy of Natural Sciences of Catania, Vol. 46, no. 376/SFE, Dec. 2013, pp. SFE18-SFE43, https://bollettino.gioenia.it/index.php/gioenia/article/view/68.