Re: Ahmad, Pollard, and Unwin: The Optimal Timing of Blood Collection during the Menstrual Cycle for the Assessment of Endogenous Sex Hormones: Can Interindividual Differences in Levels over the Whole Cycle Be Assessed on a Single Day? 11: 147–151, January 2002.
On page 147, the postal code for Dr. Tessa M. Pollard is DH1 3NH. We also wish to correct an incomplete reference on page 151. The reference should read: Waller, K., Swan, S., Windham, G., Fenster, L., Elkin, E., Lasley, B. Use of urine biomarkers to evaluate menstrual function in healthy premenopausal women. American Journal of Epidemiology, 147: 1071–1080.