@article{SIGMA_2010_6_a8,
     author = {Emanuela Caliceti and Francesco Cannata and Sandro Graffi},
     title = {$\mathcal P\mathcal T$ {Symmetric} {Schr\"odinger} {Operators:} {Reality} of the {Perturbed} {Eigenvalues}},
     journal = {Symmetry, integrability and geometry: methods and applications},
     year = {2010},
     volume = {6},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SIGMA_2010_6_a8/}
}