@article{JDM_1973__75_146629,
     author = {G.M. Petersen},
     title = {Factor sequences and their algebras {II.}},
     journal = {Jahresbericht der Deutschen Mathematiker-Vereinigung},
     pages = {140--143},
     publisher = {mathdoc},
     volume = {75},
     year = {1973},
     zbl = {0273.40004},
     url = {http://geodesic.mathdoc.fr/item/JDM_1973__75_146629/}
}