How to find Birth certificates for 1800 and before for ppl born in East Prussia,

Question:

How to find Birth certificates for 1800 and before for ppl born in East Prussia, Poland/Lithuania?

There were a lot of changes geographically and politically in those areas and i am trying to establish a birth certificate for my ggg grandad Kazimir Janulin (1831-1904) and ggg grandma Kazimira Janulina (1841-1906; dont know her maiden name) both born somewhere around Merkine area (Polish/Lithuanian territory at the time) all i know is that their parents were from east Prussia area.

Best Answer - Chosen by Asker: Hey anastasia,

Here are some sites for Polish/Lithuanian genealogy.