Genuine
Forgery A Sperati
According to the BPP book "This stamp always has the cancellation in the same position and therefore no specific test is needed, the position and impression of the cancellation being sufficient to identify this reproduction with certainty."
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Bibliography
The Work of Jean De Sperati by the British Philatelic Association 1955
Album Weeds by Rev. R. B. Earee
The Serrane Guide by Fernand Serrane
The Forged Stamps of all Countries by J. Dorn