@article{CMH_1990__65_3_140193,
     author = {Gilbert Baumslag and Peter B. Shalen},
     title = {Amalgamated products and finitely presented groups.},
     journal = {Commentarii mathematici Helvetici},
     pages = {243--254},
     publisher = {mathdoc},
     volume = {65},
     number = {3},
     year = {1990},
     zbl = {0711.20015},
     url = {http://geodesic.mathdoc.fr/item/CMH_1990__65_3_140193/}
}