@article{10_4153_CMB_1986_019_0,
     author = {Gilmer, Robert and Heinzer, William},
     title = {On the {Cardinality} of {Subrings} of a {Commutative} {Ring}},
     journal = {Canadian mathematical bulletin},
     pages = {102--108},
     year = {1986},
     volume = {29},
     number = {1},
     doi = {10.4153/CMB-1986-019-0},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1986-019-0/}
}