Arbaoui, Abdessamad, Redshaw, Carl, Elsegood, Mark R. J., Wright, Victoria E., Yoshizawa, Akina, Yamato, Takehiko, "Iron(III) and Zinc(II) calixarene complexes: Synthesis, structural studies, and use as procatalysts for ε-caprolactone polymerization", Chemistry-An Asian Journal, 2010