@article{AA_2003_15_3_a2,
     author = {F. Gesztesy and K. A. Makarov},
     title = {$\mathrm{SL}_2(\mathbb R)$, exponential {Herglotz} representations, and spectral averaging},
     journal = {Algebra i analiz},
     pages = {104--144},
     publisher = {mathdoc},
     volume = {15},
     number = {3},
     year = {2003},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AA_2003_15_3_a2/}
}