Engert, M. (1969). Problems of Long-term Planning in the German Democratic Republic. The Institute of National Planning.
Tohutoru Kātū Chicago (17th ed.)Engert, Manfred. Problems of Long-term Planning in the German Democratic Republic. Cairo: The Institute of National Planning, 1969.
Tohutoro MLA (9th ed.)Engert, Manfred. Problems of Long-term Planning in the German Democratic Republic. The Institute of National Planning, 1969.