↑ 1.01.1Cathcart, Chundra Aroor (2015年) Iranian Dialectology and Dialectometry (PhD dissertation)[1],Berkeley:University of California at Berkeley,第 32 頁:“PIr *u̯(a)r̥da-”
↑ 3.03.1Novák, Ľubomír (2013年) Problem of Archaism and Innovation in the Eastern Iranian Languages (PhD dissertation)[2],Prague:Univerzita Karlova v Praze, filozofická fakulta,第 180 頁:“u̯arda-, *u̯r̥da-”