@article{10_4153_CJM_1981_063_x,
     author = {Hill, Paul},
     title = {Criteria for {Total} {Projectivity}},
     journal = {Canadian journal of mathematics},
     pages = {817--825},
     year = {1981},
     volume = {33},
     number = {4},
     doi = {10.4153/CJM-1981-063-x},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1981-063-x/}
}