Medal commemorating first free balloon stratospheric flight of Professor Auguste Piccard and Dr. Paul Kipfer
1931
1931
1935
1926
1926
1930
1927
1938
1938
1938
1938
1935
1938
circa 1930
1931
1935
1936
1934
1929-1935
1936
1931
1937
1937
1935
1938
1938
1932
1955; 1830
1934
circa 1938
1935
1932
1933
1925-1928
1927-1929
circa 1927
circa 1930
circa 1930
1936
1925
1934
1924-1927
1935
1927
1925-1935
1932
1925-1935
before 1928
2000-100 BCE
1930-1931
Before 1932