@article{MZ_1966__92_170543,
     author = {Jaak Peetre},
     title = {Some {Estimates} for {Spectral} {Functions.}},
     journal = {Mathematische Zeitschrift},
     pages = {146--153},
     publisher = {mathdoc},
     volume = {92},
     year = {1966},
     zbl = {0151.20204},
     url = {http://geodesic.mathdoc.fr/item/MZ_1966__92_170543/}
}