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Bulgaria : growth of industrial output, 1939 and 1948-1965
Lazarcik, Gregor, (1968)
Bulgaria : a new industrial production index, 1963-1972, with extension to 1973 and 1974
Staller, George John, (1975)
Tempove i maštabi na promišlenoto proizvodstvo v NR Bŭlgarija
Draganov, Enčo, (1969)