Surface ultrastructure of Cardiocephalus longicollis (Digenea: Strigeidae) from Herring gull, Larus argentatus and its associated pathological lesions / A.A. Abdel-Aal, M.F.M Soliman, I.M. Shalaby. Helminthologia Vol. 41, no. 4 (2004), p. 175-178