@article{GDZPPN002393166, title = {Solution of a problem of R. Friedberg.}, journal = {Mathematische Zeitschrift}, volume = {82}, year = {1963}, pages = {101-103}, url = {http://dml.mathdoc.fr/item/GDZPPN002393166} }
Ellentuck, Erik. Solution of a problem of R. Friedberg.. Mathematische Zeitschrift, Tome 82 (1963) pp. 101-103. http://gdmltest.u-ga.fr/item/GDZPPN002393166/