Năm 1980 có bao nhiêu ngày Thứ 4

2/1/1980 9/1/1980 16/1/1980 23/1/1980 30/1/1980 6/2/1980 13/2/1980 20/2/1980 27/2/1980 5/3/1980 12/3/1980 19/3/1980 26/3/1980 2/4/1980 9/4/1980 16/4/1980 23/4/1980 30/4/1980 7/5/1980 14/5/1980 21/5/1980 28/5/1980 4/6/1980 11/6/1980 18/6/1980 25/6/1980 2/7/1980 9/7/1980 16/7/1980 23/7/1980 30/7/1980 6/8/1980 13/8/1980 20/8/1980 27/8/1980 3/9/1980 10/9/1980 17/9/1980 24/9/1980 1/10/1980 8/10/1980 15/10/1980 22/10/1980 29/10/1980 5/11/1980 12/11/1980 19/11/1980 26/11/1980 3/12/1980 10/12/1980 17/12/1980 24/12/1980 31/12/1980