There is no agreement about the real name and dates of Pietro Saga (sometimes Pietro de Saga). Her real name is usually stated to be Stefi Kiesler, but her first name sometimes appears as Stefani, Stefanie, Stephani, Steffi, etc. Her original surname was Fritsch or Frischer. Her dates are given as 1896-1965, 1897-1963 or 1900-1965.
In 1920 she married the Austrian architect and designer Frederick Kiesler (1890-1965), and they were involved in European avant-garde art movements, such as De Stijl. In 1926 they emigrated to the USA, and lived thereafter in New York, where they were part of the modern art scene. She was also a librarian in the New York Public Library.
This De Stijl cover is from the website of the Yale University art collection. Some of Stefi Kiesler’s typewriter art originals are also in the collection. Scroll to page 371 of: