@article{00821689, title = {The generalized Favard problem.}, journal = {Beitr\"age zur Algebra und Geometrie}, volume = {36}, year = {1995}, pages = {185-202}, zbl = {0879.52005}, language = {en}, url = {http://dml.mathdoc.fr/item/00821689} }
Kripfganz, Anita. The generalized Favard problem.. Beiträge zur Algebra und Geometrie, Tome 36 (1995) pp. 185-202. http://gdmltest.u-ga.fr/item/00821689/