P. Das, J. Baruah, and P. Tamuly, “Synthesis, Spectroscopic, Thermogravimetric and Electrochemical Characterization of Triphenylphosphineoxide Complexes of the type [MClx (Ph3PO)6-x] (M = Cu(II), Co(II), x = 2; M = Fe(III), x = 3)”, ajc, vol. 20, no. 8, pp. 5958–5966, Mar. 2010.