date spaces issue

i am using "May 6 1988" format for date.

 ValidationExpression="^(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec) (([0-9])|([0-2][0-9])|([3][0-1])) \d{4}$" />

date have to take "May  6   1988" number of spaces.

give me ValidationExpression for this.

Thanks!