@article{10_4153_CJM_1974_019_3,
     author = {Gupta, Narain and Levin, Frank and Rhemtulla, Akbar},
     title = {Chains of {Varieties}},
     journal = {Canadian journal of mathematics},
     pages = {190--206},
     year = {1974},
     volume = {26},
     number = {1},
     doi = {10.4153/CJM-1974-019-3},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1974-019-3/}
}