Hello Paolo Here is the bibliography of what I have in my library. Andrew Grebneff can probably be very accurate with the Powell history. Best Regards, Leslie Allen Crnkovic ___________ Powell, A.W.B. Note: (Shellfish of NZ 1937~1958, 1st-3rd ed) & (orig: Shellfish of NZ 1937/1946) Were taken from the bib page of the publications and appear to conflict slightly. 1957 - Shells of New Zealand: An Illustrated Handbook, 3rd Ed Enlarged (orig: Shellfish of NZ 1937/1946), Whitcombe & Tombs Pub, 202 pp, 36 pl, SB(L) 1976 - Shells of New Zealand 5th Rev Ed (Shellfish of NZ 1937~1958, 1st-3rd ed), Whitcoullis Ltd, 154 pp, 45 pl, DJ HB(M) 1979 - New Zealand Mollusca: Marine Land & Freshwater Shells, Collins Pub, 500 pp, 82 pl, 120 fig, 2 map, DJ HB(L) ___________ Abbott, R. Tucker 1954 - American Seashells, 1st Ed, 4th Pr Mar 1958, Van Nostrand, 541 pp, 32pl, 100 fig, HB(L) 1974 - American Seashells: The Marine Mollusca of the Atlantic & Pacific Coast of North America, 2nd Ed, Van Nostrand Reinhold, 663 pp, 24 cpl, 6405 id, 4000 + il, HB(L)