@article{AM2_1977__15_136632,
     author = {K.D. Jr. Magill and S. Subbiah},
     title = {The partially ordered collection of regular ...-classes of {S(X).}},
     journal = {Aequationes mathematicae},
     pages = {91--98},
     publisher = {mathdoc},
     volume = {15},
     year = {1977},
     zbl = {0349.54025},
     url = {http://geodesic.mathdoc.fr/item/AM2_1977__15_136632/}
}