@article{MV_1972_24_1_a5,
     author = {A. R. Amir-Mo\'ez and W. A. Donnell and C. R. Perry},
     title = {On the arguments of proper values of normal and unitary transformations},
     journal = {Matemati\v{c}ki vesnik},
     pages = {39 },
     publisher = {mathdoc},
     volume = {24},
     number = {1},
     year = {1972},
     url = {http://geodesic.mathdoc.fr/item/MV_1972_24_1_a5/}
}