Determination of the frequency of dyssynergic defecation and patient characteristics in patients with functional constipation - Öncü, Kemal; ÖZEL, A. Melih; Demirtürk, Levent; GÜRBÜZ, Ahmet Kemal; Yazgan, Yusuf; KIZILKAYA, Eşref (Turkish Journal of Gastroenterology, 2010)