@article{PORMA_1971__30_4_115155,
     author = {Silberger, D.M.},
     title = {Borders and roots of a word},
     journal = {Portugaliae mathematica},
     pages = {191--199},
     publisher = {mathdoc},
     volume = {30},
     number = {4},
     year = {1971},
     mrnumber = {0302791},
     zbl = {0259.20032},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1971__30_4_115155/}
}