@article{GDZPPN002411318, title = {Ends and Amalgamated Free Products of Groups.}, journal = {Mathematische Zeitschrift}, volume = {129}, year = {1972}, pages = {265-272}, zbl = {0227.20010}, url = {http://dml.mathdoc.fr/item/GDZPPN002411318} }
Oxley, Peter C. Ends and Amalgamated Free Products of Groups.. Mathematische Zeitschrift, Tome 129 (1972) pp. 265-272. http://gdmltest.u-ga.fr/item/GDZPPN002411318/