Medal commemorating first free balloon stratospheric flight of Professor Auguste Piccard and Dr. Paul Kipfer
1931
1931
1927
1935
1926
1928
1926
1926
1932
2000-100 BCE
1925
1934
1936
1935
1935
1930
1927
1933
1934
1925-1935
1939
1936
1938 and 1951
1929-1935
1927
1938
1928
1938
1925
1938
1930
1935
1938
1935
1938
circa 1930
1928
1931
1925-1927
1925-1935
1937-1938
1930-1931
1935
1936
1934
1937-1937
1929-1935
1925
1936
1931
1937