E.M.LESCRINIER,M.TESSARI,F.J.VAN KUPPEVELD, W.J.MELCHERS,C.W.HILBERS,H.A.HEUS. STRUCTURE OF THE PYRIMIDINE-RICH INTERNAL LOOP IN THE POLIOVIRUS 3'-UTR: THE IMPORTANCE OF MAINTAINING PSEUDO-2-FOLD SYMMETRY IN RNA HELICES CONTAINING TWO ADJACENT NON-CANONICAL BASE-PAIRS.. J.MOL.BIOL. V. 331 759 2003 ASTM JMOBAK UK ISSN 0022-2836