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