A. Hassan Abdel-Salam and H. A. Abo-El-Dahab, “Synthesis and Properties of Tetranuclear Octahalo Copper(II) Complexes, Pip4Cu4X8 (Pip = Piperidine, X = Cl or Br) and the Dimer Pip4Cu2Cl4 in Aprotic Media”, ajc, vol. 25, no. 13, pp. 7412–7416, Jul. 2013.