DateTime.DayOfWeekreturns a DayOfWeekgiven DateTime that does not have ToString, which supports different cultures. This is even documented :
DayOfWeek . , DateTime.ToString(String) DateTime.ToString(String, IFormatProvider) "ddd" "dddd" . ; .
DateTime
string ItalianJobCookieDayName = ItalianJobCookie.ToString("dddd");
, :
string ItalianJobCookieDayName = ItalianJobCookie.ToString("dddd", new CultureInfo("it-IT"));
, ddd dddd. .