@article{MS2_1970__26_166121,
     author = {Kung-Fu Ng},
     title = {On a {Computation} {Rule} for {Polars.}},
     journal = {Mathematica Scandinavica},
     pages = {14--16},
     publisher = {mathdoc},
     volume = {26},
     year = {1970},
     zbl = {0189.42603},
     url = {http://geodesic.mathdoc.fr/item/MS2_1970__26_166121/}
}