THE SOLUTION OF SOME PERTURBATION PROBLEMS FOR MATRICES AND SELFADJOINT OR NON-SELFADJOINT DIFFERENTIAL EQUATIONS I
- 30 June 1960
- journal article
- Published by Steklov Mathematical Institute in Russian Mathematical Surveys
- Vol. 15 (3), 1-73
- https://doi.org/10.1070/rm1960v015n03abeh004092