@article{GDZPPN002307693, title = {Invariant Means via the Ultrapower.}, journal = {Mathematische Annalen}, volume = {201}, year = {1973}, pages = {71-76}, zbl = {0235.43001}, url = {http://dml.mathdoc.fr/item/GDZPPN002307693} }
Adler, Andrew; Hamilton, James. Invariant Means via the Ultrapower.. Mathematische Annalen, Tome 201 (1973) pp. 71-76. http://gdmltest.u-ga.fr/item/GDZPPN002307693/