CΓ-PROPERTY AND APPROXIMATELY DIFFERENTIABLE FUNCTIONS Статья Isakov N.M. Mathematical Notes. Том 44. 1988. С. 833-842
THEOREMS ON THE SMOOTHNESS OF THE RIGHT INVERSE Статья Isakov N.M. Mathematical Notes. Том 41. 1987. С. 124-131
A GLOBAL PROPERTY OF APPROXIMATELY DIFFERENTIABLE FUNCTIONS Статья Isakov N.M. Mathematical Notes. Том 41. 1987. С. 280-285