Victor Maximilian Berthold, The Die Varieties of the Nesbitt Series of United States Envelopes
“ Like the famous balancing of the egg of Columbus, the problem, when solved, is extremely simple. Looking backward on the long series of failures, it seems strange that the chief characteristics have so long escaped the attention of cataloguers. The fact, however, is patent. Even as thorough and painstaking a student as the late Gilbert Harrison who, in 1895, chronicled, as he thought, all of the existing die varieties of the three cents has failed to observe the most important differences. ”
