Endoscopic ultrasound-guided fine-needle aspiration for diagnosis of solid pseudopapillary tumors of the pancreas: a multicenter experience - Jani, N; Dewitt, J; Eloubeidi, M; Varadarajulu, S; Appalaneni, V; Hoffman, B; Brugge, W; Lee, K; Khalid, A; McGrath, K (Endoscopy, 2008)