@article{10_4153_CJM_1993_066_7,
     author = {Cordes, Craig M.},
     title = {Abstract {Witt} {Rings} {When} {Certain} {Binary} {Forms} {Represent} {Exactly} {Four} {Elements}},
     journal = {Canadian journal of mathematics},
     pages = {1184--1199},
     year = {1993},
     volume = {45},
     number = {6},
     doi = {10.4153/CJM-1993-066-7},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1993-066-7/}
}