@article{10_4153_CJM_1977_082_3,
     author = {Johnson, Nancy},
     title = {Rice {Theorems} for \ensuremath{\sum}n -1 {Sets}},
     journal = {Canadian journal of mathematics},
     pages = {794--805},
     year = {1977},
     volume = {29},
     number = {4},
     doi = {10.4153/CJM-1977-082-3},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1977-082-3/}
}