@article{SF_1978__16_251456,
     author = {W. Ruppert},
     title = {A note on my paper },
     journal = {Semigroup forum},
     pages = {199--200},
     year = {1978},
     volume = {16},
     zbl = {0379.22001},
     url = {http://geodesic.mathdoc.fr/item/SF_1978__16_251456/}
}