Pham Ky Anh.
Ukr. Mat. Zh. - 1994. - 46, № 7. - pp. 956-961
A generalization of the method of coordinated approximation suggested by Yu. Gaponenko  for the space $L_2(0, 1)$ is developed for abstract Hilbeit spaces. In particular, it is shown that, for $L_2(0, 1)$, some assumptions concerning ал exact solution can be weaken.