Hafnon

References

1. https://en.wikipedia.org

2. http://tvoi-uvelirr.ru/gafnij-proisxozhdenie-gafniya-svojstva-gafniya/

3. http://pptcloud.ru/himiya/zirkoniy-gafniy

4. https://www.mindat.org/element/Hafnium

5. http://webmineral.com/chem/Chem-Hf.shtml#.We91wzBry01

6. www.handbookofmineralogy.org/