Statistika aastaraamat 1994. 1995. Latvijas Statistikas Gadaramata 1992 Statistical Yearbook of Latvia. Latvijas Republikas Valsts Statistikas Komiteja. 320 pages Lithuania's Statistics Yearbook 1991. Lithuanian Department of Statistics.
Electricity means electrical energy obtained from power stations and used in transport.
For East-Germany data of 1980 year corresponds to 1981.