Kroom
http://et.wikipedia.org/wiki/Metallid
http://upload.wikimedia.org/wikipedia/commons/thumb/5/5a/Electron_shell_024_Chromium.svg/5
58px-Electron_shell_024_Chromium.svg.png
http://www.mjtuning.ee/catalog/images/dotz.jpg
http://image.ecplaza.net/offer/h/hijackie/3906902_s.jpg
http://z.about.com/d/chemistry/1/0/C/Q/chromium.jpg
http://www.crjg.vil.ee/materjalid/oppematerjalid/keemia/7_ol%FCmpkonspekt.htm#Kroom
http://www.staff.ttu.ee/~atrik/oppe/yki0030/redoksid.pdf
http://www.terviseleht.ee/200142/42_kroom.php [6]
ael.physic.ut.ee/KF.public/Oppetyy/Loeng%204_2006.doc
http://www.eki.ee/dict/qs2006/index.cgi?Q=h%C3%BCgroskoopne&F=M&O=0&E=0
www.tlu.ee/keemia/Truusi%20%F5ppematerjalid%202006/ANORGAANILINE%20KEEMIA
%20II-1.doc
http://staff.ttu.ee/~atrik/oppe/kky3153/loeng112.pdf
http://tera.chem.ut.ee/~peeter/Loeng/YK2/l8.pdf
www.referat.ee/ee/doc/metallid2.doc
http://www.chem.ttu.ee/yki/files/K2004/elemendid/kroomi_ryhm_ee_2.pdf
http://www.chem.ttu.ee/yki/elementide_keemia/K2004
http://staff