Risk of malignancy in nonpalpable thyroid nodules: predictive value of ultrasound and color-Doppler features - Papini, E; Guglielmi, R; Bianchini, A; Crescenzi, A; Taccogna, S; Nardi, F; Panunzi, C; Rinaldi, R; Toscano, V; Pacella, C M (J Clin Endocrinol Metab, 2002)