Multi-valued maps of subsets of Euclidean spaces J. Bryszewski, Lech Górniewicz (1976) Fundamenta Mathematicae
Multivalued monotone mappings are almost everywhere single-valued P. Kenderov (1976) Studia Mathematica
Multivalued Perov-type theorems in generalized metric spaces. Guran, Liliana (2009) Surveys in Mathematics and its Applications
Multivalued solutions of a linear functional equation Wilhelmina Smajdor (1985) Annales Polonici Mathematici
Multivalued superposition operators J. Appell, E. De Pascale, P. P. Zabrejko (1991) Rendiconti del Seminario Matematico della Università di Padova
Multi-valued superpositions [Book] Jürgen Appell, Nguyêñ Hôǹg Thái, Espedito De Pascale, Petr P. Zabreĭko (1995)