Hmmm... chociazby to co google wyrzuca: http://www.google.pl/search?hl=pl&q=Har ... Google&lr=

Np.:
http://www.mtec.or.th/th/research/famd/ ... _hard.html

http://www.gordonengland.co.uk/hardness ... ion_1m.htm

http://www.corrosionsource.com/handbook/mat_hard.htm

Mam nadzieje, ze pomoglem...