Marie Curie theory of "radioactivity" (a term that she coined), techniques for isolating radioactive isotopes, and the discovery of two elements, polonium and radium. Under her direction, the world's first studies into the treatment of neoplasms were conducted using radioactive isotopes. She founded the Curie Institutes in Paris and in Warsaw, which remain major centres of medical research today. During World War I, she developed mobile radiography units to provide X-ray services to field hospitals. While a French citizen, Marie Skłodowska Curie, who used both surnames, never lost her sense of Polish identity. She taught her daughters the Polish language and took
Ève Curie and a book of war reportage, "Journey Among Warriors". From the 1960s she committed herself to work for UNICEF, providing help to children and mothers in developing countries. Ève Denise Curie was born in Paris, France on December 6, 1904. She was the younger daughter of the scientists Marie and Pierre Curie, who also had another daughter Irène (born 1897). Ève virtually did not know her father, who died in 1906 in an accident, run over by a horse cart. After this accident, Marie Curie and her daughters were supported for some time by their paternal grandfather Dr. Eugène Curie.