Glover S, Gall M, Schoenborn-Kellenberger O, Wagener M, Garnero P, Boonen S, Cauley J, Black D, Delmas P, Eastell R 2009 Establishing a reference interval for bone turnover markers in 637 healthy, young, pre-menopausal women from UK, France, Belgium, and the United States. J Bone Miner Res 24:389-397.
Dawson-Hughes B, Heaney RP, Holick MF, Lips P, Meunier PJ, Vieth R 2005 Estimates of optimal vitamin D status. Osteoporos Int 16:713-716.