using System;

using System.Collections.Generic;

using System.Linq;

using System.Globalization;

public class Program

{

    public static void Main()

    {

        DateTime reference = DateTime.Now;

        Calendar calendar = CultureInfo.CurrentCulture.Calendar;

​

        IEnumerable<int> daysInMonth = Enumerable.Range(1, calendar.GetDaysInMonth(reference.Year, reference.Month));

        List<Tuple<DateTime, DateTime>> weeks = daysInMonth.Select(day => new DateTime(reference.Year, reference.Month, day))

            .GroupBy(d => calendar.GetWeekOfYear(d, CalendarWeekRule.FirstFourDayWeek, DayOfWeek.Sunday))

            .Select(g => new Tuple<DateTime, DateTime>(g.First(), g.Last()))

            .ToList();

        weeks.ForEach(x => Console.WriteLine("{0:MM/dd/yyyy} - {1:MM/dd/yyyy}", x.Item1, x.Item2));

    }

}