@article{10_4153_CJM_1979_050_0,
     author = {Anderson, D. D. and Matijevic, J.},
     title = {Graded \ensuremath{\pi}-rings},
     journal = {Canadian journal of mathematics},
     pages = {449--457},
     year = {1979},
     volume = {31},
     number = {3},
     doi = {10.4153/CJM-1979-050-0},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1979-050-0/}
}