@article{CMH_1964__39_139290,
     author = {A. Haefliger and B. Steer},
     title = {Symmetry of {Linking} {Coefficients.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {259--270},
     publisher = {mathdoc},
     volume = {39},
     year = {1964},
     zbl = {0127.13703},
     url = {http://geodesic.mathdoc.fr/item/CMH_1964__39_139290/}
}