GDP data for the baltic states from 1988-1994 since I have to write a paper on transformation/transition processes in the baltic states (Estonia, Lithuania and Latvia), I would like to analyze GDP data from 1988 (shortly before the end of the soviet union) until now.
I already checked eurostats, the world bank and OECD databases. 
Unfortunately I couldn't find any GDP data for these countries for the period from 1988-1994.

I would highly appreciate recommendations for other databases, that might contain the data I am looking for.
The Penn World Tables for those countries goes back to 1990. Some of their indicators may even go back further but I haven't checked.

Access to them is found here