Blaabjerg O., Elg P., Gerhardt W., Hellsing K., Olafsdottir E., Penttilä I., Hyltoft Petersen P., Steensland H. and Uldall A. 1993. 6.2.4 A Nordic Reference Serum Suitable for Use as Trueness Control in the Clinical Routine Laboratory. Upsala Journal of Medical Sciences. 98, 3 (Sep. 1993), 405-412. DOI:https://doi.org/10.3109/03009739309179340.