@article{10_4153_CJM_1971_034_3,
     author = {Cramer, Timothy},
     title = {Boolean {Algebra} {Retracts}},
     journal = {Canadian journal of mathematics},
     pages = {339--344},
     year = {1971},
     volume = {23},
     number = {2},
     doi = {10.4153/CJM-1971-034-3},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1971-034-3/}
}