Return date range

My spreadsheet has a list of dates in one column. I need to know the week each date falls into. Sunday to Saturday.
Example" if a1 has a value of 09/18/2003 I am looking for a formula that will bring back the week range for that date. Range starting with Sunday-Saturday. In this case the return in b1 would be 09/14/2003 - 09/20/2003.

Any help would be greatly appreciated.
Thanks