Antique door

Antique wood door with obscure stained glass. Smaller glass panels are red, green, blue and amber with the large center piece being white obscure. 6'2 x 2'5. Has turn key doorbell, original letter slot and original design used a skeleton key. Does anyone know where I could find information on when and where it was manufactured? Any restoration tips? My plan is to restore the door to it's original condition if possible.