{{sfn|Kraatz|Metzler-Nolte|2006|p=}}

* {{cite book | last=Kraatz | first=Heinz-Bernhard | last2=Metzler-Nolte | first2=Nils | title=Concepts and Models in Bioinorganic Chemistry | publisher=Wiley-VCH | publication-place=Weinheim | date=2006-07-21 | isbn=978-3-527-31305-1}}

<ref name="v454">{{cite book | last=Kraatz | first=Heinz-Bernhard | last2=Metzler-Nolte | first2=Nils | title=Concepts and Models in Bioinorganic Chemistry | publisher=Wiley-VCH | publication-place=Weinheim | date=2006-07-21 | isbn=978-3-527-31305-1 | page=}}</ref>