G. Cendejas, C. A. Flores, F. Arreguin, A. Estrada, E. A. Flores, and F. S. Vazquez, “An Improved Understanding of the Influence of the Initiation Step on the Propylene Oxide Anionic Ring Open Polymerization”, ajc, vol. 24, no. 8, pp. 3339–3346, Apr. 2012.