@article{RLINA_1970_8_48_2_a1,
     author = {Dunninger, D. R.},
     title = {A {Picone} identity for non{\textemdash}self{\textemdash}adjoint elliptic operators},
     journal = {Atti della Accademia nazionale dei Lincei. Rendiconti della Classe di scienze fisiche, matematiche e naturali},
     pages = {133--139},
     publisher = {mathdoc},
     volume = {Ser. 8, 48},
     number = {2},
     year = {1970},
     zbl = {0195.39403},
     mrnumber = {0299926},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RLINA_1970_8_48_2_a1/}
}