engert, m. (1964). classification of industries in social countries. the institute of national planning.
Cytowanie według stylu Chicago (wyd. 17)engert, manfred. Classification of Industries in Social Countries. cairo: the institute of national planning, 1964.
Cytowanie według stylu MLA (wyd. 9)engert, manfred. Classification of Industries in Social Countries. the institute of national planning, 1964.