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Medal commemorating first free balloon stratospheric flight of Professor Auguste Piccard and Dr. Paul Kipfer
1931
1931
1927
1935
2000-100 BCE
1930
1927
1924
1925
1935
1935
circa 1930
1930-1931
1935
1936
1929-1935
1938
1938
1932
1955; 1830
circa 1938
before 1928
1932
1925-1927
1930
1926
1926
1934
1924
1927
1923
1934
1923
1936
1934
circa 1927
circa 1930
1924-1927
circa 1930
1938
1938
1938
1938
1935
1935
1939
1934
1934
1926
1936
1933