Zeylstra, W. G. (1975). Aid or development: The relevance of development aid to problems of developing countries. A.W. Sijthoff.
Lua i Stíl Chicago (17ú heag.)Zeylstra, Willem Gustaaf. Aid or Development: The Relevance of Development Aid to Problems of Developing Countries. Leyden: A.W. Sijthoff, 1975.
Lua MLA (9ú heag.)Zeylstra, Willem Gustaaf. Aid or Development: The Relevance of Development Aid to Problems of Developing Countries. A.W. Sijthoff, 1975.
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