Engraver Signed Souvenir Cards

Does anyone know of anywhere on the internet that I can find information about souvenir engraver signature signed cards? I am having a tough go at finding any information. The souvenir cards are all from Monaco and are all Roosevelt. circa 1948-1952. Any help would be greatly appreciated. I have 12 in total all different but the one posted below is just one for an example. Thanks!

It appears to be a die proof of an air mail stamp issued in 1946 ...signed by one of the engravers Charles Paul Dufresne.

Any chance of posting images of the others?

Here are the only other ones that I have on me right now. I will attempt to get more/better photos in the morning. This is 8 more on top of the other one that I posted earlier. Thanks!

They're all die proffs of the 1946 Mònaco issue, signed by the autor. Very common, and collected, on the French area.

Search for 'Epreuve D'Artiste'(artists proofs - EPA). These are one of the ways that French printed engraved stamps are issued along with regular proofs and deluxe proofs (EPL) which have all the proofs from that issued set on a single sheet. Prices vary but generally they are sought after items for the best engravers as they are issued in very small numbers.

There are some for sale here to give you an idea of prices.

http://www.philatelie-berck.com/fr/189-epreuves

Thank you very much! I greatly appreciate it!