@article{Gasser1991,
author = {Gasser, T. and Kneip, A. and Kohler, W.},
title= {A flexible and fast method for automatic smoothing},
year = {1991},
doi = {10.2307/2290393},
journal = {Journal of the American Statistical Association},
volume = {86},
number = {415},
pages = {643--652},
}