@article{RSMUP_1982__66__143_0,
     author = {Davini, Cesare},
     title = {Approximation of eigenvalues and a {Koehler's} type method},
     journal = {Rendiconti del Seminario Matematico della Universit\`a di Padova},
     pages = {143--153},
     publisher = {Seminario Matematico of the University of Padua},
     volume = {66},
     year = {1982},
     mrnumber = {664578},
     zbl = {0483.35062},
     language = {en},
     url = {http://archive.numdam.org/item/RSMUP_1982__66__143_0/}
}