Transsphenoidal resection in Cushing's disease: Undetectable serum cortisol as the definition of successful treatment - Trainer, P J; Lawrie, H S; Verhelst, J; Howlett, T A; Lowe, D G; Grossman, A B; Savage, M O; Afshar, F; Besser, G M (Clin Endocrinol, 1993)