@article{MM2_1992__76_1_155757,
     author = {Masataka Tomari and Kei-ichi Watanabe},
     title = {Normal {Zr-Graded} {Rings} and {Normal} {Cyclic} {Covers.}},
     journal = {Manuscripta mathematica},
     pages = {325--340},
     publisher = {mathdoc},
     volume = {76},
     number = {1},
     year = {1992},
     zbl = {0780.13001},
     url = {http://geodesic.mathdoc.fr/item/MM2_1992__76_1_155757/}
}