@article{10_4153_CJM_1968_058_9,
     author = {Grillet, Pierre Antoine},
     title = {Free {Pq-Algebras}},
     journal = {Canadian journal of mathematics},
     pages = {582--595},
     year = {1968},
     volume = {20},
     number = {1},
     doi = {10.4153/CJM-1968-058-9},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1968-058-9/}
}