Umberto Nobile And The "Italia"

I am trying to find out more about an Italian air mail stamp, Scott No. C7, that was overprinted "Esplorazione Polare/NOBILE/Dirigibile Italia/1928" in black. The overprint can appear on the front, the gumside, or both, and tête-bêche. The overprint was done, I believe, as a fundraising effort for Umberto Nobile's polar exploration efforts involving the airship "Italia".

One of my questions regarding the stamps involves the light green overprint which runs horizontal on the pair of stamps and vertical on the single. I can only make out the first line of the green overprint which reads "ESPLORAZIONE". The second line is pure guess work, but I'd venture "Ricerche dirigibile" which translates, I believe, to "Airship Searches".

Maybe someone on SCF has a stamp with a more legible green overprint and/or can shed some light on the background of both the black and green overprints. In addition, maybe the pencil notation on the reverse of the single stamp can be explained.

I've also a couple of post cards from this polar exploration, but that's for another inquiry in the future.

Dave









*** Moved by Staff to a more appropriate forum. ***

The green overprint always very faint reads:
Esplorazione polare ricerche Dirigibile italia, these were private overprints.Tete beche types exist.
Numerous rescue teams were sent.These stamps on cover can only be found on one of the rescue teams correspondance(Philatelic in nature).
Stamps on covers (only 25) were carried on the Dornier Wal Marin 1 rescue sea plane
sent by Italy,commanded by Capt.Ivo Ravazzoni.return flight 6-8 August.These are rare.