S. S. Massoud and H. Sigel, “Ternary Complexes in Solution: Intramolecular Stack Formation in Mixed Ligand Complexes Containing CuII, 2,2’ - Bipyridyl, and the 5’-Monophosphate of Inosine (IMP), Guanosine (GMP) o”, Chimia, vol. 44, no. 3, p. 55, Mar. 1990.