@article{SF_1983__26_134612,
     author = {J.C.S. Wong},
     title = {Left thickness, left amenability and extreme left amenability.},
     journal = {Semigroup forum},
     pages = {307--316},
     publisher = {mathdoc},
     volume = {26},
     year = {1983},
     zbl = {0509.22001},
     url = {http://geodesic.mathdoc.fr/item/SF_1983__26_134612/}
}