Caldas, M., Hatir, E., Jafari, S., & Noiri, T. (2009). A New Kupka Type Continuity, λ-Compactness and Multifunctions. CUBO, A Mathematical Journal, 11(4), 1–13. Retrieved from https://cubo.ufro.cl/ojs/index.php/cubo/article/view/1449