https://learn.microsoft.com/es-es/dotnet/api/system.globalization.datetimeformatinfo.getshortestdayname?view=netframework-4.8.1&viewFallbackFrom=netcore-3.1
DateTimeFormatInfo.GetShortestDayName(DayOfWeek) Method (System.Globalization) | Microsoft Learn
Obtains the shortest abbreviated day name for a specified day of the week associated with the current DateTimeFormatInfo object.
dayofweekmethodsystemglobalizationmicrosoft