1. [B 1] M. Sh. Birman,On the spectrum of singular boundary-value problems Mat. Sb.55 (1961), 125–174 (Russian); English transl.: Amer. Math. Soc. Transl.53 (1966), 23–80.
2. [B 2] M. Sh. Birman,Discret spectrum in the gaps of a continuous one for perturbations with large coupling constant, Adv. Soviet Math.7 (1991), 57–73.
3. [B 3] M. Sh. Birman,Discrete spectrum in the gaps of the perturbed periodic Schrödinger operator. II. Non-regular perturbations, Algebra i Analiz9, no. 6 (1997), 62–89 (Russian); English transl.: St. Petersburg Math. J.9 (1998), 1073–1095.
4. [BBor] M. Sh. Birman and V. Borzov,On the asymptotics of the discrete spectrum for certain singular differential operators, Probl. Math. Fiz.5 (1971), 24–38 (Russian); English transl.: Topics Math. Phys.5 (1972), 19–30.
5. [BLap 1] M. Sh. Birman and A. Laptev,Discrete spectrum of the perturbed Dirac operator, Ark. Mat.32 (1994), 13–32.