@article{FORUM_1991__3_2_186411,
     author = {Hans-Gerd Leopold},
     title = {On {Function} {Spaces} of {Variable} {Order} of {Differentiation.}},
     journal = {Forum mathematicum},
     pages = {1--22},
     publisher = {mathdoc},
     volume = {3},
     number = {2},
     year = {1991},
     zbl = {0737.46020},
     url = {http://geodesic.mathdoc.fr/item/FORUM_1991__3_2_186411/}
}