Forgeries
See below for larger image.
These covers first had the cover front with pen writing duplicated.The stamp was then placed manually and hand cancels applied.
Therefore the handwriting is identical between examples but the stamp placement and markings vary.
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