@article{10_4153_CJM_1968_083_1,
     author = {Kruse, Robert L.},
     title = {Rings in which all {Subrings} are {Ideals.} {I}},
     journal = {Canadian journal of mathematics},
     pages = {862--871},
     year = {1968},
     volume = {20},
     number = {1},
     doi = {10.4153/CJM-1968-083-1},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1968-083-1/}
}