CH 1944 J109-J112 Pro Juventute subscription FDC with address

Switzerland 1941 J (Pro Juventute issues)
Pro Juventute - Bildnis Numa Droz' und Alpenblumenbilder, SBK J109-112, Michel 439-442,
FDC (subscription letter), PTT-cover with address sog. Gaudard-letter, luxury quality.
This FDC is very rare to find as a set on one cover!