@article {ecol2005,
	title = {Constrained ordination analysis with flexible response functions},
	journal = {Ecological Modelling},
	volume = {187},
	number = {4},
	year = {2005},
	pages = {524{\textendash}536},
	doi = {10.1016/j.ecolmodel.2005.01.049},
	url = {http://doi.org/10.1016/j.ecolmodel.2005.01.049},
	author = {Zhu, Mu and Hastie, Trevor J. and Walther, Guenther}
}
