Canadian Embassy website: no visa required for US Green Card Hol

I researched on this recently as I'll be going to Canada.   All my friends told me no visa required.  And I also found out the info at Canadian Embassy website under Visa Exemption.   

http://www.cic.gc.ca/english/visit/visas.asp#exemptions

Visitor Visa Exemptions

Many people do not require a visa to visit Canada. These include:

persons lawfully admitted to the United States for permanent residence who are in possession of their alien registration card (Green card) or can provide other evidence of permanent residence;