@ Heinz 7 [#197]

John N. Luffs Werke kann man zum Teil sogar komplett gescannt im Netz finden:

siehe https://onlinebooks.library.upenn.edu/webbin/book/lookupname?key=Luff%2C%20John%20N%2E%20%28John%20Nicholas%29

a) The postage stamps of the United States,
by John N. Luff [1902]

https://babel.hathitrust.org/cgi/pt?id=coo1.ark:/13960/t5q81wh5q

b) Catalogue of the stamps, envelopes and wrappers of the United States of American and of the Confederate States of America,
by H. Collin and H.L. Calman with the collaboration of ... J.N. Luff and G.L. Toppan [1900].

https://babel.hathitrust.org/cgi/pt?id=uga1.32108001796187

c) Some notes on the New York postmaster's provisional five cents, black, 1845.
By O. S. Hart. With an introduction, by Hiram E. Deats. A foreword, and historical note and chapter on repints, by John N. Luff [1911].

https://babel.hathitrust.org/cgi/pt?id=hvd.hnpafk

Beste Grüße
Thomas