@article{AM2_1989__38_1_137319,
     author = {S.-L. Eriksson-Bique and H. Leutwiler},
     title = {A generalization of parallel addition.},
     journal = {Aequationes mathematicae},
     pages = {99--110},
     publisher = {mathdoc},
     volume = {38},
     number = {1},
     year = {1989},
     zbl = {0682.47024},
     url = {http://geodesic.mathdoc.fr/item/AM2_1989__38_1_137319/}
}