Παραπομπή APA

Gorle, P., & Long, J. (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.