@article{KYB_1980_16_4_a1,
     author = {Chawla, J. S.},
     title = {An invariant for continuous mappings},
     journal = {Kybernetika},
     pages = {315--317},
     year = {1980},
     volume = {16},
     number = {4},
     mrnumber = {591960},
     zbl = {0473.54032},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/KYB_1980_16_4_a1/}
}