Rotter, Ingrid Max Planck Institute for the Physics of Complex Systems, Max Planck Society;
https://link.springer.com/article/10.1140%2Fepjd%2Fe2015-60389-7 (出版社版)
1409.1149.pdf (プレプリント), 3MB
Eleuch, H., & Rotter, I. (2015). Nearby states in non-Hermitian quantum systems I: Two states. European Physical Journal D, 69(10):. doi:10.1140/epjd/e2015-60389-7.