Looking for materials about coupled slot lines

hi , i am looking for some theory, formulas and circuit modelling information of coupled slotlines.
when i search for it i found literature related to coupled microstrip or stripline but haven't come across coupled slotline ...............plz help

Check these books:
1. Mongia; Bahl; Bhartia. RF and Microwave Coupled-Line Circuits. Section 3.8. Page 117.
2. Gupta at al. Microstrip Lines and Slotlines.

hey RF-OM i am glad that u helped but the references that u have given are not about "coupled slot lines" they are about slot coupled microstrip lines.
for clearing any further doubt .......... i am looking for "coupled slot line" one can say very similar like CPW without ground (but i guess not same) and i'm very much interested in its circuit model.

if u have any idea then plz share with me

Sorry, may be you are right. These references are what I found so far. If I find more I let you know.