Get Month/Year and Week (Eg. February 2011 - week 1)

[olympiac]

I am working on a tracker and I would need a dop down list from which I can filter the data based on the weeks for each month.

I am looking for a formula that could give me this result:
February 2011 - week 1
February 2011 - week 2
February 2011 - week 3
February 2011 - week 4
March 2011 - week 1
March 2011 - week 2
etc

Is there a way to get to convert a date and get this result?

 

[stebrownsword]

=trunc(((*cel ref*-date(year(*cel ref*),1,1))/7))+1

 

[olympiac]

Great. Many thanks