They are more labels than stamps, actually they were never accepted as stamps even if some people tried (and managed) to place them after 1989 on Romanian letters, attached next to standard Romanian stamps.
Majority of them were made in Spain and you can find fast all of them here:http://timbreanticomuniste.wordpres...r-al-unesco/
Just click on the links from the right panel for going to the other "stamps".
Unfortunately, the man behind those labels was a member of the Iron Guard (he was also behind the iron guard stamps produced in Romania in 1940), the ultra-nationalist fascist party in Romania in WW II ( http://en.wikipedia.org/wiki/Iron_Guard
) so you can understand why even after the end of communism, there were not so many people trying to bring those vignette into light.