@article{10_4064_ap_8_1_13_22,
     author = {Stanis{\l}aw Go{\l}\k{a}b and A. Pli\'s},
     title = {On the notion of gradient. {III.} {Gradient} as a limit value of a surface integral},
     journal = {Annales Polonici Mathematici},
     pages = {13--22},
     publisher = {mathdoc},
     volume = {8},
     number = {1},
     year = {1960},
     doi = {10.4064/ap-8-1-13-22},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap-8-1-13-22/}
}