Voici selon Ken Potter web site la version PROOF du KENNEDY A LIRE ATTENTIVEMENT.
http://www.coinweek.com/us-type-coins-2 ... lver-1964/Designer: Gilroy Roberts, obverse; Frank Gasparro, reverse
Circulation Mintage: high 273,304,004 (1964), low 156,205,446 (1964-D)
Proof Mintage: high 3,950,762 (1964 only)Denomination: Fifty cents (50/100)
Diameter: 30.6 mm; reeded edge
Metal Content: 90% silver, 10% copper
Weight: 12.50 grams
Varieties:
A few known, including 1964 Heavily Accented Hair (proofs only; individual hairs are more apparent), 1964 and 1964-D Doubled Die Obverse; and other minor die variations.