Comparison of pooled fresh frozen serum to proficiency testing material in College of American Pathologists surveys: cortisol and immunoglobulin E.
Palmer-Toy DE, Wang E, Winter WE, Soldin SJ, Klee GG, Howanitz JH, Elin RJ. Comparison of pooled fresh frozen serum to proficiency testing material in College of American Pathologists surveys: cortisol and immunoglobulin E. Arch Pathol Lab Med. 2005 Mar; 129(3):305-9.