I have been perusing "Coins of the Popes, by Joseph Coffin, published in 1946 by Coward-McCann publishers in NYC. The dist-jacket reads:
"In 'Coins of the Popes' the author of 'Coin Collecting' has concentrated on all of the significant features of the Papal coinage, which has endured, with a few short breaks, since the time of Pope Adrian I (772-795) to Pius XII (1939-). Papal mints are enumerated, as well the the principal Papal engravers, including those who produced works of art in coinage, such as the great Benvenuto Cellini, the Hamerani, Pasinati and Pistrucci.
The book is illustrated with photographs showing inscriptions on Papal coins in Latin, and for the first time, in English from the eighth century, with scriptural references and historical significance of inscriptions and legends. One particularly interesting section deals with Christian symbols, their significance both in a general way and particulary as they relate to their inclusion on most of the papal coins. The book is an invaluable aid to collectors of ancient, medieval and modern coins, and should further appeal to lovers of history and the arts."
More to be said on this book.....