Quantum properties of the codirectional three-mode Kerr nonlinear coupler F. A.A. El-Orany, M. Sebawe Abdalla and J. Peřina Eur. Phys. J. D, 33 3 (2005) 453-463 Published online: 19 April 2004 DOI: 10.1140/epjd/e2005-00048-2