@article{PORMA_1974__33_3_115228,
     author = {Dash, A.T.},
     title = {Joint essential range},
     journal = {Portugaliae mathematica},
     pages = {133--135},
     publisher = {mathdoc},
     volume = {33},
     number = {3},
     year = {1974},
     mrnumber = {0355566},
     zbl = {0334.28006},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1974__33_3_115228/}
}