@article{10_4153_CJM_1977_096_9,
     author = {Milgram, R. James and Zvengrowski, Peter},
     title = {Even {Whitehead} {Squares} are {Not} {Projective}},
     journal = {Canadian journal of mathematics},
     pages = {957--962},
     year = {1977},
     volume = {29},
     number = {5},
     doi = {10.4153/CJM-1977-096-9},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1977-096-9/}
}