1. [1] Agmon, Shmuel Lectures on exponential decay of solutions of second-order elliptic equations: bounds on eigenfunctions of N -body Schrödinger operators, Princeton University Press, Princeton, NJ, Mathematical Notes, Tome 29 (1982), pp. 118
2. [2] Agmon, Shmuel Bounds on exponential decay of eigenfunctions of Schrödinger operators, Schrödinger operators (Como, 1984), Springer, Berlin (Lecture Notes in Math.) Tome 1159 (1985), pp. 1-38
3. [3] ArnolʼD, V. I. Remarks on the Morse theory of a divergence-free vector field, the averaging method, and the motion of a charged particle in a magnetic field, Tr. Mat. Inst. Steklova, Tome 216 (1997), pp. 9-19 (Din. Sist. i Smezhnye Vopr.)
4. [4] Charles, Laurent; Vũ Ngọc, San Spectral asymptotics via the semiclassical Birkhoff normal form, Duke Math. J., Tome 143 (2008) no. 3, pp. 463-511
5. [5] Cycon, H. L.; Froese, R. G.; Kirsch, W.; Simon, B. Schrödinger operators with application to quantum mechanics and global geometry, Springer-Verlag, Berlin, Texts and Monographs in Physics (1987), pp. x+319