@article{GDZPPN002105594,
title = {Absolutely continuous invariant measures for C2 unimodal maps satisfying the Collet-Eckmann conditions.},
journal = {Inventiones mathematicae},
volume = {93},
year = {1988},
pages = {619-636},
zbl = {0659.58034},
url = {http://dml.mathdoc.fr/item/GDZPPN002105594}
}
Nowicki, T.; Strien, S. van. Absolutely continuous invariant measures for C2 unimodal maps satisfying the Collet-Eckmann conditions.. Inventiones mathematicae, Tome 93 (1988) pp. 619-636. http://gdmltest.u-ga.fr/item/GDZPPN002105594/