mixed mode scc21

Hello I have a little problem concerning the measurement of differential S parameters for a differential amplifier.
I have to measure the conversions between differential mode and common mode using the mixed mode S parameters concepts (Eisenstadt).
Therefore I designed a differential pair and I used baluns in order to access to Sdd, Sdc, Scd and Scc. But I'm not sure what I'm measuring exactly and I need some help.

The baluns used:

http://images.elektroda.net/91_1180625563.jpg
When I measure S21 and S43, does it correspond to Sdd21 and Scc21? I"m nearly sure it is Sdd21 and Scc 21 but I don't manage to find the signification of the others.
In the list of the S parameters I have S11 S12... S14, S21...S24, ... S44.
Thanks for your response and for your help.

Dear ,
Plz refer www.rfic.co.uk
Go through the differential LNA Design. refer page 6-7.
I am confident that u will the the answer

Thanks I have already read all the circuits in particular lna design and all the circuits with differential structure. However, the author doesn't use this topology first used by William R. Eisenstadt.

In fact I have just found the answer:
Differential mode
S11=> S11
S12 S12
etc...

common mode
S33, S34, S43, S44 correspond to S11 S12 S21 S22odd