@article{MZ_1993__212_4_174502,
     author = {F. Levin and G. Rosenberger and B. Baumslag},
     title = {A cyclically pinched product of free groups which is not residually free.},
     journal = {Mathematische Zeitschrift},
     pages = {533--534},
     publisher = {mathdoc},
     volume = {212},
     number = {4},
     year = {1993},
     zbl = {0795.20014},
     url = {http://geodesic.mathdoc.fr/item/MZ_1993__212_4_174502/}
}