One of those stampdesigns made by Lon Spiegelman (USA)

A rubberstamp with history. Lon Spiegelman (USA) designed the logo for this stamp. He made a complete set of logo's for several mail-artists that were active in 1990. I transferred one logo he made into this rubberstamo which still is being used.

More details on Lon Spiegelman:

Lon Spiegelman (1941-2002) was an American mail artist and networker who initiated the concept called “Money & mail-art don't mix” stating that mail-art is non-commercial art and so can’t be bought or sold. He also coined the term “N-tity” with American mail artist Carlo Pittore, a term that refers to the spirit of networking and founded Spiegelmism Post. He was guest editor of Umbrella in the 1980s, a magazine originally started and edited by Judith A. Hoffberg.

source: http://oberlin.edu/library/art/mailart/bios/spiegelman.html