BENSON , L.; LJUNGHALL , S.; GROTH , T.; FALK , H.; HVARFNER , A.; RASTAD , J.; WIDE , L.; ÅKERSTRÖM , G. Optimal Discrimination of Mild Hyperparathyroidism with Total Serum Calcium, Ionized Calcium and Parathyroid Hormone Measurements. Upsala Journal of Medical Sciences, v. 92, n. 2, p. 147-176, 1 Sep. 1987.