Deutschland Stamps

Good afternoon..
I need some help with 4 stamps of Germany.. I don't have a recent catalog ( I use to work with SG online , but it only goes up to 2001 or 2002 .. )and I'm having problems to identify these stamps in the NET..
I think they are part of just one set.. each of them represent one season of the year, but I think they were issued at different dates.
Can You , Forum Users , help me with Catalog numbers and Year of emission ??.

Thank you..

Regards

Luis

The set of 4 is Michel #2574-2577, 9 Nov 06, catalog about $1.25 each. These are self-adhesive.

All 4 were issued previously (in 2006) as gummed stamps, #2509, #2532, #2549, and #2564, value about the same.

Thank you for Your answer..
I have now all the data I need to catalog them !..

Thank you again!.

Luis