Dyfyniad APA

Helliwell,J F. (1976). Aggregate investment: Selected readings. Penguin Education.

Dyfyniad Arddull Chicago

Helliwell,J F. Aggregate Investment: Selected Readings. England: Penguin Education, 1976.

Dyfyniad MLA

Helliwell,J F. Aggregate Investment: Selected Readings. Penguin Education, 1976.

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