[1] BERGE C.: 
Espaces topologiques. Fonctions multivoques. Paris, 1966. 
Zbl 0164.52902[2] CROSSLEY S.G., HILDEBRAND S.K.: Semi-closed sets and semicontinuity in topological spaces. Tex. J. Sci. 22, 1971, 123-126.
[4] LEVINE N.L.: 
Semi-open sets and semi-continuity in topological spaces. Amer. Math. Monthly 70, 1963, 36-41. 
MR 0166752 | 
Zbl 0113.16304[5] LIPIŃSKI J.S., ŠALÁT T.: 
On the points of quassicontinuity and cliquishness of functions. Czech. J. Math. 21 (96), 1971, 484-489. 
MR 0287517[7] PIOTROWSKI Z.: A study of certain classes of almost continuous functions on topological spaces. Doct. dissert. Wroclaw, 1979.
[8] POPA V.: 
Asupra unei decopuneri cvasicontinuitatii multifunctiolor. St. Cer. Mat. 27, 1975, 323-328. 
MR 0413041