@article{GDZPPN001260707, title = {Filters and semigroup properties.}, journal = {Semigroup forum}, volume = {40}, year = {1990}, pages = {329-338}, zbl = {0702.22005}, url = {http://dml.mathdoc.fr/item/GDZPPN001260707} }
Papazyan, T. Filters and semigroup properties.. Semigroup forum, Tome 40 (1990) pp. 329-338. http://gdmltest.u-ga.fr/item/GDZPPN001260707/