@article{10_1017_S0017089502010133,
     author = {Ferreira, Vitor de Oliveira},
     title = {Constants of derivations on free associative algebras},
     journal = {Glasgow mathematical journal},
     pages = {177--183},
     year = {2002},
     volume = {44},
     number = {1},
     doi = {10.1017/S0017089502010133},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089502010133/}
}