UNITED NATIONS (1976) Conference on Human Settlements*. Set of 12 imperforate progressive proofs. Scott No 277, Yvert No 268. From the UN printer archives. Rare!
AVAILABLE AT $100
UNITED NATIONS (1982) Hands holding seedling*. Set of 8 imperforate progressive proof pairs. Scott No 371, Yvert No 362. From the UN printer archives. Rare!
AVAILABLE AT $100
MONACO (1972) Three stages of environment (before, during and after pollution)*. Full sheet of 10 trial color proofs. Scott No 827, Yvert No 881.
AVAILABLE AT $250