Monday.
15 December 1958 was a Monday.
15 January 1958 was a Wednesday.
November 15, 1958 was a Saturday.
May 15, 1958 fell on a Thursday.
Monday
It was a Sunday.
It was a Friday.
Saturday.
15 September 1995 was a Friday.
15 September 1821 was a Saturday.
15 September 1996 was a Sunday.
September 15 1997 was on a Monday.