Ruokonen , A., P. Hyltoft-Petersen, and O. Blaabjerg. “External Quality Assurance Model for Improvement of Specificity and Assuracy of Serum Hormone Determinations in the Nordic Countries”. Upsala Journal of Medical Sciences 95, no. 3 (September 1, 1990): 257-258. Accessed March 26, 2026. https://ujms.net/index.php/ujms/article/view/6780.