equivalent circuit for a nadmittance bridge

Hello :

Recently, for the School, we did buy from Surplus, a old Scheinleitwertmessbrücke ( 0,5 to 30 Mhz), model SWM 2-2 from VEB messelektronik Berlin (1971) . Somebody could indicate to us as it is his equivalent circuit? .( I can send pictures ). Thanks in advance.

Joaquin