AUSTRIA (1973) Vienna Hofburg Gate*. ISI Emblem*. Black print. Scott No 948, Yvert No 1249. 39th Congress International Statistical Institute.
AVAILABLE AT $20
GERMANY (1966) Leibnitz*. Photo essay (See Note) of unaccepted design for 250th anniversary of death. Scott No 962, Yvert No 375.
AVAILABLE AT $75
AUSTRIA (1979) Population chart*. Angel*. Black proof, 150th anniversary of Austrian Central Statistical Bureau. Scott No 1120, Yvert No 1436.
AVAILABLE AT $15
AUSTRIA (1981) Escher's "Impossible" Cube*. Black print. Scott No 1187, Yvert No 1509. 10th International Mathematicians Congress.
AVAILABLE AT $20