@article{GDZPPN00124826X, title = {When is a functionally free algebra free?}, journal = {Semigroup forum}, volume = {4}, year = {1972}, pages = {177-184}, zbl = {0255.08004}, url = {http://dml.mathdoc.fr/item/GDZPPN00124826X} }
Evans, T. When is a functionally free algebra free?. Semigroup forum, Tome 4 (1972) pp. 177-184. http://gdmltest.u-ga.fr/item/GDZPPN00124826X/