engert, m. (1964). classification of industries in social countries. the institute of national planning.
Cita Chicago (17th ed.)engert, manfred. Classification of Industries in Social Countries. cairo: the institute of national planning, 1964.
Cita MLA (9th ed.)engert, manfred. Classification of Industries in Social Countries. the institute of national planning, 1964.
Atenció: Aquestes cites poden no estar 100% correctes.