@article{MS2_1978__42_166572,
     author = {Istv\'an Beck and Peter J. Trosborg},
     title = {A note on free direct summands.},
     journal = {Mathematica Scandinavica},
     pages = {34--38},
     publisher = {mathdoc},
     volume = {42},
     year = {1978},
     zbl = {0382.16015},
     url = {http://geodesic.mathdoc.fr/item/MS2_1978__42_166572/}
}