Kehr, E. A. (1956). Vatican: The stamps and description of their designs and background prepared especially for stamp collectors. The Washington Press.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रKehr, Ernest A. Vatican: The Stamps and Description of Their Designs and Background Prepared Especially for Stamp Collectors. Newark, New Jersey: The Washington Press, 1956.
एमएलए (8वां संस्करण) प्रशस्ति पत्रKehr, Ernest A. Vatican: The Stamps and Description of Their Designs and Background Prepared Especially for Stamp Collectors. The Washington Press, 1956.
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