@article{03798121, title = {On the Ritt order of a certain class of functions.}, journal = {International Journal of Mathematics and Mathematical Sciences}, volume = {6}, year = {1983}, pages = {181-187}, doi = {10.1155/S0161171283000162}, zbl = {0506.30017}, language = {en}, url = {http://dml.mathdoc.fr/item/03798121} }
Parvatham, R.; Thangamani, J. On the Ritt order of a certain class of functions.. International Journal of Mathematics and Mathematical Sciences, Tome 6 (1983) pp. 181-187. doi : 10.1155/S0161171283000162. http://gdmltest.u-ga.fr/item/03798121/