Robby Keuleers Herman O. Desseyn Giannis S. Papaefstathiou Labrini Drakopoulou Spyros P. Perlepes Catherine P. Raptopoulou Aris Terzis, Hydrogen-bonded networks based on manganese(II), nickel(II), copper(II) and zinc(II) complexes of N,N′-dimethylurea, Transition Metal Chemistry, (28), 548--557, 2003, Springer Science and Business Media LLC, 0340-4285