Woodman, T. J., Sarazin, Y., Fink, G., Hauschild, K., & Bochmann, M. (2005). Heterogenized "ligand-Free" lanthanide catalysts for the homo- and copolymerization of ethylene and 1,3-butadiene. Macromolecules, 38(8), 3060-3067. doi:10.1021/ma047454r.