Voir la notice de l'article provenant de la source Czech Digital Mathematics Library
@article{ARM_1991__27_1-2_a1, author = {Dr\'a\v{s}il, Milan and Novotn\'y, Miroslav}, title = {A characterization of harmonic languages}, journal = {Archivum mathematicum}, pages = {7--14}, publisher = {mathdoc}, volume = {27}, number = {1-2}, year = {1991}, mrnumber = {1189636}, zbl = {0792.68080}, language = {en}, url = {http://geodesic.mathdoc.fr/item/ARM_1991__27_1-2_a1/} }
Drášil, Milan; Novotný, Miroslav. A characterization of harmonic languages. Archivum mathematicum, Tome 27 (1991) no. 1-2, pp. 7-14. http://geodesic.mathdoc.fr/item/ARM_1991__27_1-2_a1/