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