Vitamin D intake is low and hypovitaminosis D common in healthy 9- to 15-yeat-old Finnish girls - Lehtonen-Veromaa, M; Möttönen, T; Irjala, K; Kärkkäinen, M; Lamberg-Allardt, C; Hakola, P; Viikari, J (Eur J Clin Nutr, 1999)