Оригинальный текст - Английский - Calendars

It is not a mistake that in all Calendars around the world Monday is held to be the first day of the week, by default. It is for a few reasons. ISO 8601 defines Monday as the first day of the week, making Sunday the seventh. Moreover, in most of countries in the world Monday refers to the first day of the week. Finally, Saturday and Sunday are commonly called the weekend. As Sunday is weekEND, it cannot be the beginning of the week, logically.