Stamate, Cristina. “Vector Subdifferentials and Tangent Cones”. Rev. Anal. Numér. Théor. Approx. 34, no. 2 (August 1, 2005): 207–226. Accessed November 24, 2024. https://ictp.acad.ro/jnaat/journal/article/view/2005-vol34-no2-art9.