any
10-12 c.
13 cent.
13-16 c.
10-19th cent.
16 cent.
17 cent.
18 cent.
1812
18-19th cent.
19 cent.
18 cent. - 1917
1862
1868
1883
1900-1917
1901-14
19-20 cent.
1914-18
1918
1919
1921-1937
1918-40
1926-1932
1927-1935
1939- 45
1940-41
1941-45
1967
1945-90
1945 - 1999
20-21 cent
21cent
The Riga Hydro-Electric power station.
Construction of the hydro-electric power station
Kegums HES
Edgar Frantzman with sons
Workers and engineers