@article{10_4153_CJM_1981_032_3,
     author = {Gordon, C. Mca. and Litherland, R. A. and Murasugi, K.},
     title = {Signatures of {Covering} {Links}},
     journal = {Canadian journal of mathematics},
     pages = {381--394},
     year = {1981},
     volume = {33},
     number = {2},
     doi = {10.4153/CJM-1981-032-3},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1981-032-3/}
}