title: Long-term variation in serum 25-hydroxyvitamin D concentration among participants in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial.
authors.affiliation: Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, 6120 Executive Boulevard, EPS 8109, Bethesda, MD 20892-7240, USA. hofmannjn@mail.nih.gov
authors.forename: Jonathan N
authors.initials: JN
authors.lastname: Hofmann
authors.forename: Kai
authors.initials: K
authors.lastname: Yu
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Horst
authors.forename: Richard B
authors.initials: RB
authors.lastname: Hayes
authors.forename: Mark P
authors.initials: MP
authors.lastname: Purdue