Παραπομπή σε μορφή APA (7η εκδ.)

Cowan, D. H., & Weller, C. D. (1984). Preferred provider organizations: Planning, structure, and operation. Aspen Systems Corporation.

Παραπομπή σε μορφή Chicago (17η εκδ.)

Cowan, Dale H., και Charles D. Weller. Preferred Provider Organizations: Planning, Structure, and Operation. Rockville: Aspen Systems Corporation, 1984.

Παραπομπή σε μορφή MLA (8th εκδ.)

Cowan, Dale H., και Charles D. Weller. Preferred Provider Organizations: Planning, Structure, and Operation. Aspen Systems Corporation, 1984.