@article{GDZPPN002539314, title = {Secondary invariants for links}, journal = {Revista colombiana de matematicas}, volume = {6}, year = {1972}, pages = {106-115}, zbl = {0254.57011}, url = {http://dml.mathdoc.fr/item/GDZPPN002539314} }
Gutiérrez, M. A. Secondary invariants for links. Revista colombiana de matematicas, Tome 6 (1972) pp. 106-115. http://gdmltest.u-ga.fr/item/GDZPPN002539314/