@article{SF_1986__35_134875,
     author = {P. Olin},
     title = {Normal forms for band free products.},
     journal = {Semigroup forum},
     pages = {265--278},
     publisher = {mathdoc},
     volume = {35},
     year = {1986},
     zbl = {0615.20040},
     url = {http://geodesic.mathdoc.fr/item/SF_1986__35_134875/}
}