1. [1] Borsuk, Karol. Theory of retracts. Vol. 44 of Mathematical Monographs. Warsaw: PWN - Polish Scientific Publishers, 1967. Cited on 35.
2. [2] Engelking, Ryszard. General topology. Vol. 60 of Mathematical Monographs. Warsaw: PWN - Polish Scientific Publishers, 1977. Cited on 41 and 47.
3. [3] Gabor, Grzegorz, Lech Górniewicz and Mirosław Ślosarski. “Generalized topological essentiality and coincidence points of multivalued maps.” Set-Valued Var. Anal. 17, no. 1 (2009): 1-19. Cited on 35.
4. [4] Górniewicz, Lech. Topological fixed point theory of multivalued mappings. Second edition. Vol. 4 of Topological Fixed Point Theory and Its Applications. Dordrecht: Springer, 2006. Cited on 35, 36, 37, 41, 48 and 49.
5. [5] Górniewicz, Lech. “Topological degree and its applications to differential inclusions.” Raccolta di Seminari del Dipartimento di Matematica dell’Universita degli Studi della Calabria, March-April, 1983. Cited on 42.