Baškienė, Angelė. “On Normality of Parabolic (φ, ξ  η,  λ)-Structures”. Lietuvos matematikos rinkinys 43, no. spec. (December 22, 2003): 161–164. Accessed May 20, 2024. https://www.journals.vu.lt/LMR/article/view/32375.