http://translate.google.sk/translate?hl=sk&sl=cs&u=cs.wikipedia.org/wiki/Proterozoikum&ei=9uWYT-jyA4nZ4QTbrfTEBg&sa=X&oi=translate&ct=result&resnum=2&ved=0CDAQ7gEwAQ&prev=/search%3Fq%3Dstarohory%2Bwikipedia%26hl%3Dsk%26biw%3D1440%26bih%3D707%26prmd%3Dimvns
http://www.google.sk/url?sa=t&rct=j&q=prvohory%20wikipedia&source=web&cd=1&ved=0CCcQFjAA&url=http%3A%2F%2Fsk.wikipedia.org%2Fwiki%2FPaleozoikum&ei=MOyYT5m9MIWB4gS16JjFBg&usg=AFQjCNHt3sV3NHqHmMqQU5hXyNiBL5Dm1g&cad=rja
http://sk.wikipedia.org/wiki/Mezozoikum
http://sk.wikipedia.org/wiki/Terci%C3%A9r
http://sk.wikipedia.org/wiki/Kvart%C3%A9r