@article{AM2_1985__28_137035,
     author = {W.T. Tutte},
     title = {Mediations on the product rule.},
     journal = {Aequationes mathematicae},
     pages = {13--21},
     publisher = {mathdoc},
     volume = {28},
     year = {1985},
     zbl = {0581.05007},
     url = {http://geodesic.mathdoc.fr/item/AM2_1985__28_137035/}
}