Source
Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:
"File:Oxidationszahlen%2520Ethan.svg%2520-%2520Wikipedia,%2520the%2520free%2520encyclopedia."
http://en.wikipedia.org/w/index.php?title=File:Oxidationszahlen_Ethan.svg&page=1
Wikipedia
Public domain.
