Intrinsic near-24-h pacemaker period determines limits of circadian entrainment to a weak synchronizer in humans.
Wright KP, Hughes RJ, Kronauer RE, Dijk DJ, Czeisler CA. Intrinsic near-24-h pacemaker period determines limits of circadian entrainment to a weak synchronizer in humans. Proc Natl Acad Sci U S A. 2001 Nov 20; 98(24):14027-32.