@article{PORMA_1977__36_3-4_115324,
     author = {Lo, Chi Yeung},
     title = {Boundary value problems of generalized axially symmetric {Helmholtz} equations},
     journal = {Portugaliae mathematica},
     pages = {279--289},
     publisher = {mathdoc},
     volume = {36},
     number = {3-4},
     year = {1977},
     mrnumber = {0597850},
     zbl = {0446.35041},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1977__36_3-4_115324/}
}