APA-viite (7. p.)

Elshafei, A. (1968). Product Performance Models PPM. The Institute of National Planning.

Chicago-viite (17. p.)

Elshafei, Alwalid. Product Performance Models PPM. Cairo: The Institute of National Planning, 1968.

MLA-viite (9. p.)

Elshafei, Alwalid. Product Performance Models PPM. The Institute of National Planning, 1968.

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