Παραπομπή APA

Gorle Peter & James Long. (1973). Essentials of product planning. McGraw hill.

Παραπομπή Chicago Style

Gorle Peter και James Long. Essentials of Product Planning. London: McGraw hill, 1973.

Παραπομπή MLA

Gorle Peter και James Long. Essentials of Product Planning. McGraw hill, 1973.