On subspaces of an intermediate characteristic in $C^*$
V. I. Zalyapin, L. D. Menikhes, G. A. Shefer

References
1.	Tikhonov A.N., Arsenin V.Ya., Methods for solving ill-posed problems, Nauka Publ., Moscow, 1986, 287 pp. (In Russ.)
2.	Vinokurov V.A., Petunin Yu.I., Plichko A.N., “Condition for mesurability and regularizability of mappings, which are inverse for continuous linear operators”, Reports of the USSR Academy of Sciences, 220:3 (1975), 509–511 (In Russ.)
3.	Menikhes L.D., “On the regularizability of mappings, which are inverse to integral operators”, Reports of the USSR Academy of Sciences, 241:1 (1978), 282–285 (In Russ.)
4.	Menikhes L.D., “Regularizability of some classes of mappings that are inverses of integral operators”, Mathematical Notes, 65:2 (1999), 181–187
5.	Dunford N., Schwartz J.T., Linear Operators. Part I: General Theory, Wiley-Interscience, Hoboken, New Jersy, 1988, 872 pp.