@article{MZ_1968__108_171112,
     author = {Abraham Karrass and Donald Solitar},
     title = {On {Finitely} {Generated} {Subgroups} of a {Free} {Product.}},
     journal = {Mathematische Zeitschrift},
     pages = {285--287},
     publisher = {mathdoc},
     volume = {108},
     year = {1968},
     zbl = {0182.03601},
     url = {http://geodesic.mathdoc.fr/item/MZ_1968__108_171112/}
}