Count one month in a dates range.

I am having difficulties finding the right formula to calculate how many selected months are in a range of dates.

D11 | E11 | F11
--------------------------------------------
Name | Date1 | Date2
--------------------------------------------
Personnel 1 | 05-Mar-14 | 12-Apr-14
Personnel 2 | 21-Jul-14 | 03-Aug-14
Personnel 3 | 06-Oct-14 | 19-Oct-14
Personnel 4 | 22-Dec-14 | 04-Jan-15

I want to Count how many Mar, Apr, Jul, ... etc.

Thank you.