Παραπομπή σε μορφή APA (7η εκδ.)

Kehr, E. A. (1956). Vatican: The stamps and description of their designs and background prepared especially for stamp collectors. The Washington Press.

Παραπομπή σε μορφή Chicago (17η εκδ.)

Kehr, Ernest A. Vatican: The Stamps and Description of Their Designs and Background Prepared Especially for Stamp Collectors. Newark, New Jersey: The Washington Press, 1956.

Παραπομπή σε μορφή MLA (8th εκδ.)

Kehr, Ernest A. Vatican: The Stamps and Description of Their Designs and Background Prepared Especially for Stamp Collectors. The Washington Press, 1956.